Limit Kansas itemized deductions to the four K.S.A. 79-32,120(a) categories at each year's shares

[MaxGhenis]

WIP (draft). Pending: targeted YAML runs (queued under the hub heavy lock), main-vs-branch households, the microsimulation (held by Fleet ops), an independent review and the Axiom parity item.

What changes

K.S.A. 79-32,120(a) defines the Kansas itemized deduction as four federal categories at year-specific shares:

Tax years	Charitable contributions (§170)	Medical care (§213)	Qualified residence interest (§163(h))	Real and personal property taxes (§164(a))
2015–2017	100%	—	50%	50%
2018	100%	50%	50%	50%
2019	100%	75%	75%	75%
2020 on	100%	100%	100%	100%

Main used itemized_deductions_less_salt + real_estate_taxes, so it gave 100% of every federal non-SALT itemized deduction in every year. That included investment interest (inside interest_deduction), casualty and theft losses, pre-2018 miscellaneous deductions and the 2020–2021 charitable deduction for non-itemizers. The branch adds four dated share parameters and sums only those categories. Qualified residence interest is deductible_mortgage_interest_tax_unit, not interest_deduction.

It also applies (a)(1)(A): "For all tax years prior to tax year 2021, if federal taxable income of an individual is determined by itemizing deductions … such individual may elect to deduct the Kansas itemized deduction in lieu of the Kansas standard deduction." (a)(1)(B) drops that condition from 2021. Main let everyone itemize in every year.

Law

• K.S.A. 79-32,120(a)(5): "For the tax years commencing on and after January 1, 2020, the Kansas itemized deduction of an individual means the following deductions from federal adjusted gross income … (A) 100% of charitable contributions … (B) 100% of expenses for medical care … (C) 100% of the amount of qualified residence interest … and (D) 100% of the amount of taxes on real and personal property as provided in section 164(a)…" Subsections (a)(2)–(4) give the earlier shares in the table. https://www.ksrevisor.gov/statutes/chapters/ch79/079_032_0120.html
• 2017 K-40 instructions, Schedule S Part C (PDF p.14): lines C1–C3 take 50% of real estate taxes, personal property taxes and mortgage interest; C4 takes gifts to charity. https://www.ksrevenue.gov/pdf/ip17.pdf#page=14
• 2018 and 2019 K-40 instructions (PDF p.2): 100% charity and 50% (2018) or 75% (2019) of medical, residential interest and property taxes. "You may only itemize your deductions on your Kansas return if you itemized deductions on your federal return." https://www.ksrevenue.gov/pdf/ip18.pdf#page=2
• 2025 K-40 instructions, Kansas Schedule A (PDF p.14): medical (lines 1–4), property taxes (5–7), interest (8–9), charity (10–13). https://www.ksrevenue.gov/pdf/ip25.pdf#page=14

Personal property taxes have no separate PE input, so only real_estate_taxes enters.

Coordination

• Model the claim of right repayment deduction and credit (26 U.S.C. 1341) and North Carolina's rules that depend on it #10038 subtracts claim_of_right_deduction and Count gambling winnings in federal gross income and fix the wagering losses deduction #10070 subtracts wagering_losses_deduction from main's federal sum here. The closed list never includes either, so whichever lands after this drops its Kansas formula edit. Their new Kansas test cases still hold under this formula.

Tests

(pending)

Invariants

• Kansas itemized deductions = Σ share × category, over the four K.S.A. 79-32,120(a) categories, with each share in [0, 1]. So they never exceed charity + medical + qualified residence interest + property taxes.
• Investment interest, casualty and theft losses, miscellaneous deductions and the non-itemizer charitable deduction never change them (YAML cases 3 and 7).
• Before 2021, a filer who does not itemize federally always gets the Kansas standard deduction; from 2021 the larger deduction applies (ks_taxable_income cases 4–6).

Microsimulation

(pending; Fleet ops hold)

axiom: (pending)

🤖 Generated with Claude Code