From 05a8b802747a84c66ef21700a426dac2c2c1a443 Mon Sep 17 00:00:00 2001
From: alexis-anthonissen <alexis.anthonissen@acsone.eu>
Date: Wed, 23 Sep 2026 15:14:13 +0200
Subject: [PATCH 1/2] [IMP] contract - add invoice offset configurations

---
 contract/models/contract.py                   |   2 +
 contract/models/contract_line.py              |  45 +++----
 contract/models/contract_recurring_mixin.py   |  84 +++++++-----
 contract/tests/test_contract.py               | 122 ++++++++++++++----
 contract/views/contract.xml                   |  13 ++
 contract/views/contract_line.xml              |   2 +
 contract/views/contract_template_line.xml     |   5 +
 contract_forecast/models/contract_line.py     |   1 +
 .../models/contract_line.py                   |   2 +
 .../models/contract_line.py                   |   1 +
 product_contract/models/product_template.py   |  18 +++
 product_contract/models/sale_order_line.py    |  11 +-
 .../models/sale_order_line_contract_mixin.py  |  22 ++++
 .../contract_configurator_controller.esm.js   |   4 +
 .../static/src/js/sale_product_field.esm.js   |   4 +
 product_contract/views/product_template.xml   |  13 ++
 product_contract/views/sale_order.xml         |   7 +
 .../product_contract_configurator_views.xml   |  13 ++
 18 files changed, 278 insertions(+), 91 deletions(-)

diff --git a/contract/models/contract.py b/contract/models/contract.py
index ddcc91ade6..de940296e0 100644
--- a/contract/models/contract.py
+++ b/contract/models/contract.py
@@ -170,6 +170,7 @@ def _compute_invoice_count(self):
         "next_period_date_start",
         "recurring_invoicing_type",
         "recurring_invoicing_offset",
+        "recurring_invoicing_offset_type",
         "recurring_rule_type",
         "recurring_interval",
         "date_end",
@@ -195,6 +196,7 @@ def _compute_recurring_next_date(self):
                     contract.next_period_date_start,
                     contract.recurring_invoicing_type,
                     contract.recurring_invoicing_offset,
+                    contract.recurring_invoicing_offset_type,
                     contract.recurring_rule_type,
                     contract.recurring_interval,
                     max_date_end=contract.date_end,
diff --git a/contract/models/contract_line.py b/contract/models/contract_line.py
index 23efbc4744..2c6cd0bd51 100644
--- a/contract/models/contract_line.py
+++ b/contract/models/contract_line.py
@@ -60,26 +60,6 @@ def _compute_display_name(self):
         for rec in self:
             rec.display_name = f"{rec.date_start} - {rec.name}"
 
-    @api.model
-    def _compute_first_recurring_next_date(
-        self,
-        date_start,
-        recurring_invoicing_type,
-        recurring_rule_type,
-        recurring_interval,
-    ):
-        # deprecated method for backward compatibility
-        return self.get_next_invoice_date(
-            date_start,
-            recurring_invoicing_type,
-            self._get_default_recurring_invoicing_offset(
-                recurring_invoicing_type, recurring_rule_type
-            ),
-            recurring_rule_type,
-            recurring_interval,
-            max_date_end=False,
-        )
-
     def _get_analytic_distribution_arguments(self):
         self.ensure_one()
         partner_categ_ids = self.contract_id.partner_id.category_id.ids
@@ -100,7 +80,12 @@ def _compute_analytic_distribution(self):
                 ]._get_distribution(line._get_analytic_distribution_arguments())
                 line.analytic_distribution = distribution or line.analytic_distribution
 
-    @api.constrains("recurring_next_date", "date_start")
+    @api.constrains(
+        "recurring_next_date",
+        "date_start",
+        "recurring_invoicing_offset",
+        "recurring_invoicing_offset_type",
+    )
     def _check_recurring_next_date_start_date(self):
         for line in self:
             if (
@@ -109,7 +94,16 @@ def _check_recurring_next_date_start_date(self):
             ):
                 continue
             if line.date_start and line.recurring_next_date:
-                if line.date_start > line.recurring_next_date:
+                if (
+                    line.date_start
+                    + self._get_invoicing_offset_relative_delta(
+                        line.recurring_invoicing_type,
+                        line.recurring_rule_type,
+                        line.recurring_invoicing_offset,
+                        line.recurring_invoicing_offset_type,
+                    )
+                    > line.recurring_next_date
+                ):
                     raise ValidationError(
                         self.env._(
                             "You can't have a date of next invoice anterior "
@@ -163,8 +157,7 @@ def _check_recurring_next_date_recurring_invoices(self):
             ):
                 raise ValidationError(
                     self.env._(
-                        "You must supply a date of next invoice for contract "
-                        "line '%s'"
+                        "You must supply a date of next invoice for contract line '%s'"
                     )
                     % rec.name
                 )
@@ -176,8 +169,7 @@ def _check_start_end_dates(self):
                 if line.date_start > line.date_end:
                     raise ValidationError(
                         self.env._(
-                            "Contract line '%s' start date can't be later than"
-                            " end date"
+                            "Contract line '%s' start date can't be later than end date"
                         )
                         % line.name
                     )
@@ -243,6 +235,7 @@ def _get_period_to_invoice(
             next_invoice_date=recurring_next_date,
             recurring_invoicing_type=self.recurring_invoicing_type,
             recurring_invoicing_offset=self.recurring_invoicing_offset,
+            recurring_invoicing_offset_type=self.recurring_invoicing_offset_type,
         )
         return first_date_invoiced, last_date_invoiced, recurring_next_date
 
diff --git a/contract/models/contract_recurring_mixin.py b/contract/models/contract_recurring_mixin.py
index 88b1659fb3..780090f446 100644
--- a/contract/models/contract_recurring_mixin.py
+++ b/contract/models/contract_recurring_mixin.py
@@ -59,13 +59,23 @@ class ContractRecurringMixin(models.AbstractModel):
         ),
     )
     recurring_invoicing_offset = fields.Integer(
-        compute="_compute_recurring_invoicing_offset",
         string="Invoicing offset",
         help=(
             "Number of days to offset the invoice from the period end "
             "date (in post-paid mode) or start date (in pre-paid mode)."
         ),
     )
+    recurring_invoicing_offset_type = fields.Selection(
+        selection=[
+            ("daily", "Day(s)"),
+            ("weekly", "Week(s)"),
+            ("monthly", "Month(s)"),
+            ("quarterly", "Quarter(s)"),
+            ("semesterly", "Semester(s)"),
+            ("yearly", "Year(s)"),
+        ],
+        string="Invoicing offset type",
+    )
     # === Invoicing Configuration Fields ===
     # Define when and how invoices should be issued within the recurrence.
 
@@ -109,6 +119,7 @@ def _compute_next_period_date_start(self):
         "next_period_date_start",
         "recurring_invoicing_type",
         "recurring_invoicing_offset",
+        "recurring_invoicing_offset_type",
         "recurring_rule_type",
         "recurring_interval",
         "date_end",
@@ -125,21 +136,14 @@ def _compute_next_period_date_end(self):
                 next_invoice_date=rec.recurring_next_date,
                 recurring_invoicing_type=rec.recurring_invoicing_type,
                 recurring_invoicing_offset=rec.recurring_invoicing_offset,
-            )
-
-    @api.depends("recurring_invoicing_type", "recurring_rule_type")
-    def _compute_recurring_invoicing_offset(self):
-        """Compute the invoicing offset based on type and rule."""
-        for rec in self:
-            method = self._get_default_recurring_invoicing_offset
-            rec.recurring_invoicing_offset = method(
-                rec.recurring_invoicing_type, rec.recurring_rule_type
+                recurring_invoicing_offset_type=rec.recurring_invoicing_offset_type,
             )
 
     @api.depends(
         "next_period_date_start",
         "recurring_invoicing_type",
         "recurring_invoicing_offset",
+        "recurring_invoicing_offset_type",
         "recurring_rule_type",
         "recurring_interval",
         "date_end",
@@ -151,6 +155,7 @@ def _compute_recurring_next_date(self):
                 rec.next_period_date_start,
                 rec.recurring_invoicing_type,
                 rec.recurring_invoicing_offset,
+                rec.recurring_invoicing_offset_type,
                 rec.recurring_rule_type,
                 rec.recurring_interval,
                 max_date_end=rec.date_end,
@@ -186,6 +191,7 @@ def get_next_period_date_end(
         next_invoice_date=False,
         recurring_invoicing_type=False,
         recurring_invoicing_offset=False,
+        recurring_invoicing_offset_type=False,
     ):
         """Compute the end date for the next period."""
         if not next_period_date_start or (
@@ -202,17 +208,20 @@ def get_next_period_date_end(
             )
         else:
             # Forced invoice date: back-calculate period end
-            if recurring_invoicing_type == "pre-paid":
-                next_period_date_end = (
-                    next_invoice_date
-                    - relativedelta(days=recurring_invoicing_offset)
-                    + self.get_relative_delta(recurring_rule_type, recurring_interval)
-                    - relativedelta(days=1)
-                )
-            else:  # post-paid
-                next_period_date_end = next_invoice_date - relativedelta(
-                    days=recurring_invoicing_offset
+            next_period_date_end = (
+                next_invoice_date
+                - self._get_invoicing_offset_relative_delta(
+                    recurring_invoicing_type,
+                    recurring_rule_type,
+                    recurring_invoicing_offset,
+                    recurring_invoicing_offset_type,
                 )
+            )
+
+            if recurring_invoicing_type == "pre-paid":
+                next_period_date_end += self.get_relative_delta(
+                    recurring_rule_type, recurring_interval
+                ) - relativedelta(days=1)
 
         if max_date_end and next_period_date_end > max_date_end:
             next_period_date_end = max_date_end
@@ -224,6 +233,7 @@ def get_next_invoice_date(
         next_period_date_start,
         recurring_invoicing_type,
         recurring_invoicing_offset,
+        recurring_invoicing_offset_type,
         recurring_rule_type,
         recurring_interval,
         max_date_end,
@@ -239,20 +249,36 @@ def get_next_invoice_date(
             return False
 
         if recurring_invoicing_type == "pre-paid":
-            return next_period_date_start + relativedelta(
-                days=recurring_invoicing_offset
-            )
+            next_invoice_date = next_period_date_start
         else:
-            return next_period_date_end + relativedelta(days=recurring_invoicing_offset)
+            next_invoice_date = next_period_date_end
+
+        return next_invoice_date + self._get_invoicing_offset_relative_delta(
+            recurring_invoicing_type,
+            recurring_rule_type,
+            recurring_invoicing_offset,
+            recurring_invoicing_offset_type,
+        )
 
     @api.model
-    def _get_default_recurring_invoicing_offset(
-        self, recurring_invoicing_type, recurring_rule_type
+    def _get_invoicing_offset_relative_delta(
+        self,
+        recurring_invoicing_type,
+        recurring_rule_type,
+        recurring_invoicing_offset,
+        recurring_invoicing_offset_type,
     ):
-        """Return default offset in days based on invoicing type and rule."""
         if (
             recurring_invoicing_type == "pre-paid"
             or recurring_rule_type == "monthlylastday"
         ):
-            return 0
-        return 1
+            invoice_offset = relativedelta()
+        else:
+            invoice_offset = relativedelta(days=1)
+
+        if recurring_invoicing_offset != 0 and recurring_invoicing_offset_type:
+            invoice_offset += self.get_relative_delta(
+                recurring_invoicing_offset_type, recurring_invoicing_offset
+            )
+
+        return invoice_offset
diff --git a/contract/tests/test_contract.py b/contract/tests/test_contract.py
index 6a4727f49a..1ecd6d564c 100644
--- a/contract/tests/test_contract.py
+++ b/contract/tests/test_contract.py
@@ -670,22 +670,6 @@ def test_act_show_contract(self):
             "There was an error and the view couldn't be opened.",
         )
 
-    def test_get_default_recurring_invoicing_offset(self):
-        clm = self.env["contract.line"]
-        self.assertEqual(
-            clm._get_default_recurring_invoicing_offset("pre-paid", "monthly"), 0
-        )
-        self.assertEqual(
-            clm._get_default_recurring_invoicing_offset("post-paid", "monthly"), 1
-        )
-        self.assertEqual(
-            clm._get_default_recurring_invoicing_offset("pre-paid", "monthlylastday"), 0
-        )
-        self.assertEqual(
-            clm._get_default_recurring_invoicing_offset("post-paid", "monthlylastday"),
-            0,
-        )
-
     def test_get_next_invoice_date(self):
         """Test different combination to compute recurring_next_date
         Combination format
@@ -705,16 +689,18 @@ def error_message(
             date_start,
             recurring_invoicing_type,
             recurring_invoicing_offset,
+            recurring_invoicing_offset_type,
             recurring_rule_type,
             recurring_interval,
             max_date_end,
         ):
             return (
-                "Error in %s-%d every %d %s case, "
+                "Error in %s-%d %s every %d %s case, "
                 "start with %s (max_date_end=%s)"
                 % (
                     recurring_invoicing_type,
                     recurring_invoicing_offset,
+                    recurring_invoicing_offset_type,
                     recurring_interval,
                     recurring_rule_type,
                     date_start,
@@ -725,7 +711,7 @@ def error_message(
         combinations = [
             (
                 to_date("2018-01-01"),
-                (to_date("2018-01-01"), "pre-paid", 0, "monthly", 1, False),
+                (to_date("2018-01-01"), "pre-paid", 0, None, "monthly", 1, False),
             ),
             (
                 to_date("2018-01-01"),
@@ -733,6 +719,7 @@ def error_message(
                     to_date("2018-01-01"),
                     "pre-paid",
                     0,
+                    None,
                     "monthly",
                     1,
                     to_date("2018-01-15"),
@@ -744,6 +731,7 @@ def error_message(
                     to_date("2018-01-16"),
                     "pre-paid",
                     0,
+                    None,
                     "monthly",
                     1,
                     to_date("2018-01-15"),
@@ -751,11 +739,11 @@ def error_message(
             ),
             (
                 to_date("2018-01-01"),
-                (to_date("2018-01-01"), "pre-paid", 0, "monthly", 2, False),
+                (to_date("2018-01-01"), "pre-paid", 0, None, "monthly", 2, False),
             ),
             (
                 to_date("2018-02-01"),
-                (to_date("2018-01-01"), "post-paid", 1, "monthly", 1, False),
+                (to_date("2018-01-01"), "post-paid", 1, None, "monthly", 1, False),
             ),
             (
                 to_date("2018-01-16"),
@@ -763,6 +751,7 @@ def error_message(
                     to_date("2018-01-01"),
                     "post-paid",
                     1,
+                    None,
                     "monthly",
                     1,
                     to_date("2018-01-15"),
@@ -774,6 +763,7 @@ def error_message(
                     to_date("2018-01-16"),
                     "post-paid",
                     1,
+                    None,
                     "monthly",
                     1,
                     to_date("2018-01-15"),
@@ -781,31 +771,63 @@ def error_message(
             ),
             (
                 to_date("2018-03-01"),
-                (to_date("2018-01-01"), "post-paid", 1, "monthly", 2, False),
+                (to_date("2018-01-01"), "post-paid", 1, None, "monthly", 2, False),
             ),
             (
                 to_date("2018-01-31"),
-                (to_date("2018-01-05"), "post-paid", 0, "monthlylastday", 1, False),
+                (
+                    to_date("2018-01-05"),
+                    "post-paid",
+                    0,
+                    None,
+                    "monthlylastday",
+                    1,
+                    False,
+                ),
             ),
             (
                 to_date("2018-01-06"),
-                (to_date("2018-01-06"), "pre-paid", 0, "monthlylastday", 1, False),
+                (
+                    to_date("2018-01-06"),
+                    "pre-paid",
+                    0,
+                    None,
+                    "monthlylastday",
+                    1,
+                    False,
+                ),
             ),
             (
                 to_date("2018-02-28"),
-                (to_date("2018-01-05"), "post-paid", 0, "monthlylastday", 2, False),
+                (
+                    to_date("2018-01-05"),
+                    "post-paid",
+                    0,
+                    None,
+                    "monthlylastday",
+                    2,
+                    False,
+                ),
             ),
             (
                 to_date("2018-01-05"),
-                (to_date("2018-01-05"), "pre-paid", 0, "monthlylastday", 2, False),
+                (
+                    to_date("2018-01-05"),
+                    "pre-paid",
+                    0,
+                    None,
+                    "monthlylastday",
+                    2,
+                    False,
+                ),
             ),
             (
                 to_date("2018-01-05"),
-                (to_date("2018-01-05"), "pre-paid", 0, "yearly", 1, False),
+                (to_date("2018-01-05"), "pre-paid", 0, None, "yearly", 1, False),
             ),
             (
                 to_date("2019-01-05"),
-                (to_date("2018-01-05"), "post-paid", 1, "yearly", 1, False),
+                (to_date("2018-01-05"), "post-paid", 1, None, "yearly", 1, False),
             ),
         ]
         contract_line_env = self.env["contract.line"]
@@ -1723,3 +1745,49 @@ def test_contract_line_total_value_period_prorata(self):
         self.assertEqual(
             self.acct_line._get_contract_line_total_value(), expected_total
         )
+
+    def test_get_next_invoice_date_with_offset_type(self):
+        """Offset values use the selected recurrence unit."""
+        contract_line_env = self.env["contract.line"]
+        date_start = to_date("2018-01-01")
+
+        expected_dates = {
+            "daily": to_date("2018-01-02"),
+            "weekly": to_date("2018-01-08"),
+            "monthly": to_date("2018-02-01"),
+            "quarterly": to_date("2018-04-01"),
+            "semesterly": to_date("2018-07-01"),
+            "yearly": to_date("2019-01-01"),
+        }
+
+        for offset_type, expected_date in expected_dates.items():
+            self.assertEqual(
+                contract_line_env.get_next_invoice_date(
+                    date_start,
+                    "pre-paid",
+                    1,
+                    offset_type,
+                    "monthly",
+                    1,
+                    False,
+                ),
+                expected_date,
+            )
+
+    def test_get_next_period_date_end_with_offset_type(self):
+        """The period end is back-calculated using the offset type."""
+        contract_line_env = self.env["contract.line"]
+
+        self.assertEqual(
+            contract_line_env.get_next_period_date_end(
+                to_date("2018-01-01"),
+                "monthly",
+                1,
+                max_date_end=False,
+                next_invoice_date=to_date("2018-02-08"),
+                recurring_invoicing_type="post-paid",
+                recurring_invoicing_offset=1,
+                recurring_invoicing_offset_type="weekly",
+            ),
+            to_date("2018-01-31"),
+        )
diff --git a/contract/views/contract.xml b/contract/views/contract.xml
index 36e19ed76e..8f0eaa22ba 100644
--- a/contract/views/contract.xml
+++ b/contract/views/contract.xml
@@ -305,6 +305,19 @@
                                             nolabel="1"
                                         />
                                     </div>
+                                    <label for="recurring_invoicing_offset" />
+                                    <div class="o_row">
+                                        <field
+                                            name="recurring_invoicing_offset"
+                                            class="oe_inline"
+                                            nolabel="1"
+                                        />
+                                        <field
+                                            name="recurring_invoicing_offset_type"
+                                            class="oe_inline"
+                                            nolabel="1"
+                                        />
+                                    </div>
                                 </group>
                                 <group>
                                     <field name="invoice_partner_id" required="1" />
diff --git a/contract/views/contract_line.xml b/contract/views/contract_line.xml
index 846dd0f880..9e9dc95e43 100644
--- a/contract/views/contract_line.xml
+++ b/contract/views/contract_line.xml
@@ -106,6 +106,8 @@
                 <field name="date_start" column_invisible="True" />
                 <field name="date_end" />
                 <field name="recurring_next_date" column_invisible="True" />
+                <field name="recurring_invoicing_offset" optional="hide" />
+                <field name="recurring_invoicing_offset_type" optional="hide" />
                 <field name="last_date_invoiced" groups="base.group_no_one" />
                 <field name="create_invoice_visibility" column_invisible="True" />
             </list>
diff --git a/contract/views/contract_template_line.xml b/contract/views/contract_template_line.xml
index fd25c2d453..b06c09d4d9 100644
--- a/contract/views/contract_template_line.xml
+++ b/contract/views/contract_template_line.xml
@@ -77,6 +77,11 @@
                                 </group>
                                 <group>
                                     <field name="recurring_invoicing_type" />
+                                    <label for="recurring_invoicing_offset" />
+                                    <div class="o_row">
+                                        <field name="recurring_invoicing_offset" />
+                                        <field name="recurring_invoicing_offset_type" />
+                                    </div>
                                 </group>
                             </group>
                         </page>
diff --git a/contract_forecast/models/contract_line.py b/contract_forecast/models/contract_line.py
index b73287b344..e8f8a8fd56 100644
--- a/contract_forecast/models/contract_line.py
+++ b/contract_forecast/models/contract_line.py
@@ -106,6 +106,7 @@ def _generate_forecast_periods(self):
                         period_date_start,
                         rec.recurring_invoicing_type,
                         rec.recurring_invoicing_offset,
+                        rec.recurring_invoicing_offset_type,
                         rec.recurring_rule_type,
                         rec.recurring_interval,
                         max_date_end=max_date_end,
diff --git a/contract_line_successor/models/contract_line.py b/contract_line_successor/models/contract_line.py
index 597658a652..b217530126 100644
--- a/contract_line_successor/models/contract_line.py
+++ b/contract_line_successor/models/contract_line.py
@@ -387,6 +387,7 @@ def _delay(self, delay_delta):
                 new_date_start,
                 rec.recurring_invoicing_type,
                 rec.recurring_invoicing_offset,
+                rec.recurring_invoicing_offset_type,
                 rec.recurring_rule_type,
                 rec.recurring_interval,
                 max_date_end=new_date_end,
@@ -457,6 +458,7 @@ def _prepare_value_for_plan_successor(
                 date_start,
                 self.recurring_invoicing_type,
                 self.recurring_invoicing_offset,
+                self.recurring_invoicing_offset_type,
                 self.recurring_rule_type,
                 self.recurring_interval,
                 max_date_end=date_end,
diff --git a/contract_refund_on_stop/models/contract_line.py b/contract_refund_on_stop/models/contract_line.py
index 7352346f5a..0262d7418e 100644
--- a/contract_refund_on_stop/models/contract_line.py
+++ b/contract_refund_on_stop/models/contract_line.py
@@ -107,6 +107,7 @@ def _get_refund_on_stop_quantity(self, to_refund_start_date, to_refund_end_date)
                 to_refund_start_date,
                 self.recurring_invoicing_type,
                 self.recurring_invoicing_offset,
+                self.recurring_invoicing_offset_type,
                 self.recurring_rule_type,
                 self.recurring_interval,
                 max_date_end=next_period_date_end,
diff --git a/product_contract/models/product_template.py b/product_contract/models/product_template.py
index 75c579376b..853024f02b 100644
--- a/product_contract/models/product_template.py
+++ b/product_contract/models/product_template.py
@@ -59,6 +59,24 @@ class ProductTemplate(models.Model):
         help="Define whether invoices are issued before (prepaid) or after (postpaid) "
         "the service period.",
     )
+    recurring_invoicing_offset = fields.Integer(
+        string="Invoicing offset",
+        help=(
+            "Number of days to offset the invoice from the period end "
+            "date (in post-paid mode) or start date (in pre-paid mode)."
+        ),
+    )
+    recurring_invoicing_offset_type = fields.Selection(
+        selection=[
+            ("daily", "Day(s)"),
+            ("weekly", "Week(s)"),
+            ("monthly", "Month(s)"),
+            ("quarterly", "Quarter(s)"),
+            ("semesterly", "Semester(s)"),
+            ("yearly", "Year(s)"),
+        ],
+        string="Invoicing offset type",
+    )
     is_auto_renew = fields.Boolean(string="Auto Renew", default=False)
     termination_notice_interval = fields.Integer(
         default=1, string="Termination Notice Before"
diff --git a/product_contract/models/sale_order_line.py b/product_contract/models/sale_order_line.py
index 78a0827b96..c6daf8538d 100644
--- a/product_contract/models/sale_order_line.py
+++ b/product_contract/models/sale_order_line.py
@@ -48,14 +48,6 @@ def _prepare_contract_line_values(
         :return: new contract line dict
         """
         self.ensure_one()
-        recurring_next_date = self.env[
-            "contract.line"
-        ]._compute_first_recurring_next_date(
-            self.date_start or fields.Date.today(),
-            self.recurring_invoicing_type,
-            self.recurring_rule_type,
-            1,
-        )
         termination_notice_interval = self.product_id.termination_notice_interval
         termination_notice_rule_type = self.product_id.termination_notice_rule_type
         return {
@@ -68,10 +60,11 @@ def _prepare_contract_line_values(
             "discount": self.discount,
             "date_end": self.date_end,
             "date_start": self.date_start or fields.Date.today(),
-            "recurring_next_date": recurring_next_date,
             "recurring_interval": self.recurring_interval,
             "recurring_invoicing_type": self.recurring_invoicing_type,
             "recurring_rule_type": self.recurring_rule_type,
+            "recurring_invoicing_offset": self.recurring_invoicing_offset,
+            "recurring_invoicing_offset_type": self.recurring_invoicing_offset_type,
             "is_auto_renew": self.is_auto_renew,
             "auto_renew_interval": self.auto_renew_interval,
             "auto_renew_rule_type": self.auto_renew_rule_type,
diff --git a/product_contract/models/sale_order_line_contract_mixin.py b/product_contract/models/sale_order_line_contract_mixin.py
index a6e3c0608c..7477a9a4b7 100644
--- a/product_contract/models/sale_order_line_contract_mixin.py
+++ b/product_contract/models/sale_order_line_contract_mixin.py
@@ -80,6 +80,24 @@ class SaleOrderLineContractMixin(models.AbstractModel):
         store=True,
         readonly=False,
     )
+    recurring_invoicing_offset = fields.Integer(
+        string="Invoicing offset",
+        help=(
+            "Number of days to offset the invoice from the period end "
+            "date (in post-paid mode) or start date (in pre-paid mode)."
+        ),
+    )
+    recurring_invoicing_offset_type = fields.Selection(
+        selection=[
+            ("daily", "Day(s)"),
+            ("weekly", "Week(s)"),
+            ("monthly", "Month(s)"),
+            ("quarterly", "Quarter(s)"),
+            ("semesterly", "Semester(s)"),
+            ("yearly", "Year(s)"),
+        ],
+        string="Invoicing offset type",
+    )
     date_start = fields.Date(
         compute="_compute_contract_line_date_start",
         store=True,
@@ -174,6 +192,8 @@ def _compute_product_contract_data(self):
                 "recurring_interval": 0,
                 "recurring_rule_type": False,
                 "recurring_invoicing_type": False,
+                "recurring_invoicing_offset": False,
+                "recurring_invoicing_offset_type": False,
                 "recurrence_interval": False,
                 "is_auto_renew": False,
                 "auto_renew_interval": False,
@@ -187,6 +207,8 @@ def _compute_product_contract_data(self):
                     "recurring_interval": p.recurring_interval,
                     "recurring_rule_type": p.recurring_rule_type,
                     "recurring_invoicing_type": p.recurring_invoicing_type,
+                    "recurring_invoicing_offset": p.recurring_invoicing_offset,
+                    "recurring_invoicing_offset_type": p.recurring_invoicing_offset_type,  # noqa: E501
                     "recurrence_interval": p.recurrence_interval,
                     "is_auto_renew": p.is_auto_renew,
                     "auto_renew_interval": p.auto_renew_interval,
diff --git a/product_contract/static/src/js/contract_configurator_controller.esm.js b/product_contract/static/src/js/contract_configurator_controller.esm.js
index 2f4d38095e..28c1004b4b 100644
--- a/product_contract/static/src/js/contract_configurator_controller.esm.js
+++ b/product_contract/static/src/js/contract_configurator_controller.esm.js
@@ -16,6 +16,8 @@ export class ProductContractConfiguratorController extends formView.Controller {
             recurring_rule_type,
             recurrence_interval,
             recurring_invoicing_type,
+            recurring_invoicing_offset,
+            recurring_invoicing_offset_type,
             contract_id,
             date_start,
             date_end,
@@ -32,6 +34,8 @@ export class ProductContractConfiguratorController extends formView.Controller {
             recurring_rule_type,
             recurrence_interval,
             recurring_invoicing_type,
+            recurring_invoicing_offset,
+            recurring_invoicing_offset_type,
             contract_id,
             date_start,
             date_end,
diff --git a/product_contract/static/src/js/sale_product_field.esm.js b/product_contract/static/src/js/sale_product_field.esm.js
index 74315b8080..f6cec5daac 100644
--- a/product_contract/static/src/js/sale_product_field.esm.js
+++ b/product_contract/static/src/js/sale_product_field.esm.js
@@ -61,6 +61,10 @@ patch(SaleOrderLineProductField.prototype, {
             default_recurring_rule_type: this.props.record.data.recurring_rule_type,
             default_recurring_invoicing_type:
                 this.props.record.data.recurring_invoicing_type,
+            default_recurring_invoicing_offset:
+                this.props.record.data.recurring_invoicing_offset,
+            default_recurring_invoicing_offset_type:
+                this.props.record.data.recurring_invoicing_offset_type,
             default_product_uom_qty: this.props.record.data.product_uom_qty,
             default_contract_id: this.props.record.data.contract_id[0],
             default_recurring_interval: this.props.record.data.recurring_interval,
diff --git a/product_contract/views/product_template.xml b/product_contract/views/product_template.xml
index d115dd9bee..23b5b5b41d 100644
--- a/product_contract/views/product_template.xml
+++ b/product_contract/views/product_template.xml
@@ -56,6 +56,19 @@
                                 />
                             </div>
                             <field name="recurring_invoicing_type" />
+                            <label for="recurring_invoicing_offset" />
+                            <div class="o_row">
+                                <field
+                                    name="recurring_invoicing_offset"
+                                    class="oe_inline"
+                                    nolabel="1"
+                                />
+                                <field
+                                    name="recurring_invoicing_offset_type"
+                                    class="oe_inline"
+                                    nolabel="1"
+                                />
+                            </div>
                         </group>
                     </group>
                     <group string="Renewal">
diff --git a/product_contract/views/sale_order.xml b/product_contract/views/sale_order.xml
index e65c82123c..58d99f298d 100644
--- a/product_contract/views/sale_order.xml
+++ b/product_contract/views/sale_order.xml
@@ -75,6 +75,11 @@
                 </group>
                 <group invisible="not is_contract">
                     <field name="recurring_invoicing_type" />
+                    <label for="recurring_invoicing_offset" />
+                    <div class="o_row">
+                        <field name="recurring_invoicing_offset" />
+                        <field name="recurring_invoicing_offset_type" />
+                    </div>
                 </group>
                 <group invisible="not is_contract">
                     <field name="date_start" required="is_contract" />
@@ -126,6 +131,8 @@
                 <field name="recurring_interval" optional="hide" />
                 <field name="recurring_rule_type" optional="hide" />
                 <field name="recurring_invoicing_type" optional="hide" />
+                <field name="recurring_invoicing_offset" optional="hide" />
+                <field name="recurring_invoicing_offset_type" optional="hide" />
                 <field name="contract_start_date_method" column_invisible="1" />
                 <field
                     name="date_start"
diff --git a/product_contract/wizards/product_contract_configurator_views.xml b/product_contract/wizards/product_contract_configurator_views.xml
index 15cfa4da9b..49aeca8386 100644
--- a/product_contract/wizards/product_contract_configurator_views.xml
+++ b/product_contract/wizards/product_contract_configurator_views.xml
@@ -44,6 +44,19 @@
                             />
                         </div>
                         <field name="recurring_invoicing_type" />
+                        <label for="recurring_invoicing_offset" />
+                        <div class="o_row">
+                            <field
+                                name="recurring_invoicing_offset"
+                                class="oe_inline"
+                                nolabel="1"
+                            />
+                            <field
+                                name="recurring_invoicing_offset_type"
+                                class="oe_inline"
+                                nolabel="1"
+                            />
+                        </div>
                     </group>
                 </group>
 

From 8377c9559260165cbaaaa33021bb908a40882063 Mon Sep 17 00:00:00 2001
From: bosd <5e2fd43-d292-4c90-9d1f-74ff3436329a@anonaddy.me>
Date: Thu, 1 Oct 2026 13:56:13 +0200
Subject: [PATCH 2/2] [DOC] contract: explain the invoicing offset in the
 readme

The offset is the part of the recurrence that is hardest to picture, so
show it rather than describe it: a table of worked examples for one March
period, pre-paid and post-paid, positive and negative.

Negative values are worth spelling out, since invoicing a month up front
is probably the main reason to reach for the field, and nothing says so
today.

Generated README.rst and index.html are left out on purpose. My local
oca-gen-addon-readme rewrites the page title and drops the OCA banner
against what 18.0 has committed, and that noise does not belong in your
branch.
---
 contract/readme/USAGE.md | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/contract/readme/USAGE.md b/contract/readme/USAGE.md
index 8cc5f31818..75d7239467 100644
--- a/contract/readme/USAGE.md
+++ b/contract/readme/USAGE.md
@@ -16,6 +16,8 @@
       period in the invoice line description
     - pre-paid (invoice at period start) or post-paid (invoice at start
       of next period)
+    - an invoicing offset, to move the invoice away from that date (see
+      below)
 4.  The "Generate Recurring Invoices from Contracts" cron runs daily to
     generate the invoices. If you are in debug mode, you can click on
     the invoice creation button.
@@ -36,3 +38,31 @@
 ![image](../static/src/screenshots/portal-list.png)
 
 ![image](../static/src/screenshots/portal-detail.png)
+
+## Shifting the invoice date
+
+*Invoicing type* says whether a period is billed at its start (pre-paid)
+or after it has run (post-paid). *Invoicing offset* moves that date, in
+the unit chosen next to it.
+
+A positive offset delays the invoice. A negative one issues it earlier,
+which is how you invoice up front: set `-1` with *Month(s)* on a pre-paid
+monthly line and the invoice for March is raised on 1 February.
+
+For a period running from 1 to 31 March, billed monthly:
+
+| Invoicing type | Offset | Unit    | Invoice issued |
+|----------------|-------:|---------|----------------|
+| Pre-paid       |      0 | Day(s)  | 1 March        |
+| Pre-paid       |     -1 | Month(s)| 1 February     |
+| Pre-paid       |     15 | Day(s)  | 16 March       |
+| Post-paid      |      0 | Day(s)  | 1 April        |
+| Post-paid      |      2 | Week(s) | 15 April       |
+| Post-paid      |    -10 | Day(s)  | 22 March       |
+
+Post-paid already includes the day after the period ends, which is why an
+offset of 0 lands on 1 April rather than 31 March.
+
+The quickest way to check a setting is to watch *Date of Next Invoice* on
+the line. It recomputes as soon as the offset changes, so the effect is
+visible before anything is invoiced.