diff --git a/hknweb/forms.py b/hknweb/forms.py
index 70e4c514..45498f04 100644
--- a/hknweb/forms.py
+++ b/hknweb/forms.py
@@ -17,6 +17,11 @@
 
 import secrets
 
+import functools
+import operator
+
+from django.db.models import Q
+
 from hknweb.models import User, Profile
 from hknweb.coursesemester.models import Semester
 from hknweb.utils import get_rand_photo
@@ -200,9 +205,15 @@ def save(self):
             )
 
         def email_to_username(email: str) -> str:
+            # Normalize to lowercase so that emails differing only in case (e.g.
+            # "Jane.Doe@berkeley.edu" vs "jane.doe@berkeley.edu") map to the same
+            # username, and so that the "@berkeley.edu" suffix check isn't case
+            # sensitive either.
+            normalized_email = email.lower()
+
             username = None
-            if email.endswith(required_email_suffix):
-                username = email[: -len(required_email_suffix)]
+            if normalized_email.endswith(required_email_suffix.lower()):
+                username = normalized_email[: -len(required_email_suffix)]
 
             return username
 
@@ -220,11 +231,19 @@ def email_to_username(email: str) -> str:
 
             row["username"] = username
 
-        existing_usernames = set(
-            User.objects.filter(username__in=usernames).values_list(
+        # Compare case-insensitively: a DB user "JaneDoe" should still be treated
+        # as a duplicate of a newly-derived username "janedoe".
+        existing_usernames_query = functools.reduce(
+            operator.or_,
+            (Q(username__iexact=username) for username in usernames),
+            Q(pk__in=[]),
+        )
+        existing_usernames = {
+            username.lower()
+            for username in User.objects.filter(existing_usernames_query).values_list(
                 "username", flat=True
             )
-        )
+        }
 
         # Setup account provisioning utils
         # Get candidate group to add users to
@@ -240,7 +259,8 @@ def generate_password() -> str:
 
         email_information = []
         for row in rows:
-            # If username is None or already exists, skip provisioning
+            # If username is None or already exists (including a duplicate earlier
+            # in this same batch), skip provisioning
             if (row["username"] is None) or (row["username"] in existing_usernames):
                 continue
 
@@ -257,6 +277,10 @@ def generate_password() -> str:
             )
             user.save()
 
+            # Track this username so a later row in the same batch with the same
+            # email (differing only in case) is treated as a duplicate too.
+            existing_usernames.add(row["username"])
+
             # Add user to the candidates group
             group.user_set.add(user)
 
diff --git a/tests/test_provision_candidates_form.py b/tests/test_provision_candidates_form.py
new file mode 100644
index 00000000..c9723466
--- /dev/null
+++ b/tests/test_provision_candidates_form.py
@@ -0,0 +1,86 @@
+import io
+
+from django.conf import settings
+from django.contrib.auth.models import Group, User
+from django.core.files.uploadedfile import SimpleUploadedFile
+from django.test import TestCase
+
+from hknweb.forms import ProvisionCandidatesForm
+
+
+def _make_csv_upload(rows):
+    """Build an in-memory CSV upload matching the form's required columns.
+
+    ``rows`` is a list of (first_name, last_name, email) tuples.
+    """
+    buffer = io.StringIO()
+    buffer.write("First name,Last name,Berkeley email\r\n")
+    for first_name, last_name, email in rows:
+        buffer.write(f"{first_name},{last_name},{email}\r\n")
+
+    return SimpleUploadedFile(
+        "candidates.csv",
+        buffer.getvalue().encode("utf-8"),
+        content_type="text/csv",
+    )
+
+
+class ProvisionCandidatesFormTests(TestCase):
+    def setUp(self):
+        Group.objects.get_or_create(name=settings.CAND_GROUP)
+
+    def test_duplicate_emails_within_same_batch_differing_only_in_case(self):
+        # Two rows for the "same" candidate whose email only differs by case.
+        # Only one account should be created, and the form should not raise.
+        upload = _make_csv_upload(
+            [
+                ("Jane", "Doe", "Jane.Doe@berkeley.edu"),
+                ("Jane", "Doe", "jane.doe@berkeley.edu"),
+            ],
+        )
+
+        form = ProvisionCandidatesForm(data={}, files={"file": upload})
+        self.assertTrue(form.is_valid(), form.errors)
+
+        form.save()
+
+        self.assertEqual(
+            User.objects.filter(username__iexact="jane.doe").count(),
+            1,
+        )
+        self.assertEqual(len(form.email_information), 1)
+
+    def test_duplicate_email_against_existing_user_differing_only_in_case(self):
+        # An account already exists with a differently-cased username. A new
+        # upload deriving the same username (case-insensitively) should be
+        # skipped instead of raising an IntegrityError.
+        User.objects.create_user(
+            username="John.Smith",
+            email="John.Smith@berkeley.edu",
+            password="irrelevant",
+        )
+
+        upload = _make_csv_upload([("John", "Smith", "john.smith@berkeley.edu")])
+
+        form = ProvisionCandidatesForm(data={}, files={"file": upload})
+        self.assertTrue(form.is_valid(), form.errors)
+
+        form.save()
+
+        self.assertEqual(
+            User.objects.filter(username__iexact="john.smith").count(),
+            1,
+        )
+        self.assertEqual(len(form.email_information), 0)
+
+    def test_new_candidate_is_still_created_normally(self):
+        upload = _make_csv_upload([("Alice", "Nguyen", "alice.nguyen@berkeley.edu")])
+
+        form = ProvisionCandidatesForm(data={}, files={"file": upload})
+        self.assertTrue(form.is_valid(), form.errors)
+
+        form.save()
+
+        user = User.objects.get(username="alice.nguyen")
+        self.assertEqual(user.email, "alice.nguyen@berkeley.edu")
+        self.assertEqual(len(form.email_information), 1)