Which Year-End Move Cuts a Retiree's 2026 Tax Most?

Which year-end tax move cuts a retiree's 2026 tax the most?

It depends on the household. Two moves led most often, tied: QCD instead of cash (median change −$1,717 where it applied) and Harvest losses (median change −$607 where it applied) cut the 2026 total most for 5 of the 12 households each. No single move won everywhere: 3 different moves came first. A Roth conversion never lowers 2026 tax; $25,000 converted cost 16.0% to 98.7% of the amount in 2026, depending on the household.

Twelve retiree households, each run through the seven moves a retiree can still make for 2026, at three sizes each, by the module behind the Year-end Tax Moves tool. Every number is the change in the household's 2026 total: federal income tax (with any RMD excise and underpayment penalty), state income tax, the IRMAA surcharge 2026 income sets for 2028 Medicare premiums, and the ACA premium tax credit.

The twelve households

Which move cuts each household's 2026 total most?

"Take the rest of the RMD" cuts the total by removing the 25% excise on an RMD not taken by December 31; "Q4 estimate or December withholding" by lowering the underpayment penalty. Bunching moves 2027–2028 deductions into 2026: the 2026 cut shown here comes back as higher tax in those years (the tool shows the three-year comparison).

The Roth conversion: a 2026 cost and a marginal rate

The highest rates are the ACA households: their conversion pushed household income over 400% of the poverty line, where the whole 2026 premium credit ends. A conversion is tax paid in 2026 at a known rate in place of tax on the same dollars later. Whether it pays depends on the rate those dollars would face later, which this study does not assume.

Moves together are not the sum of moves alone

Where the two differ, a threshold sits between them: a bracket edge, the Social Security taxation formula, the senior-deduction phase-out, a state exclusion limit, or a cliff (an IRMAA tier, 400% of the poverty line).

Every move at three sizes

Run the seven moves on your own 2026 numbers
Free: your 2026 baseline, one move in full and your combined total.

Download the data

Every row on this page, with its inputs: year-end-tax-moves-2026.csv · year-end-tax-moves-2026.json (CC0).

Questions

What year-end moves can a retiree still make for 2026?

A Roth conversion, harvesting losses, harvesting long-term gains in the 0% band, bunching charitable giving, a QCD instead of a cash gift, taking the rest of the RMD, and a fourth-quarter estimated payment or extra December withholding. All but the estimate (due January 15, 2027) must be done by December 31, 2026; a first RMD can wait until April 1, 2027.

Does a Roth conversion lower 2026 tax?

No. It adds ordinary income to 2026, so 2026 tax rises; it can also raise 2028 Medicare premiums and lower an ACA credit. It is a choice to pay at today's rate instead of a later one.

Why is doing several moves not the sum of doing each one?

Because the moves share the same thresholds. A QCD that lowers income can open room for a conversion; a loss harvest changes how much gain fits in the 0% band; together two moves can cross a bracket edge or an IRMAA tier that neither crosses alone.

Are these my numbers?

No. They are twelve illustrative households. The Year-end Tax Moves tool runs the same calculation on your own numbers.

Sources and method

Every figure was computed by the module behind Year-end Tax Moves, which runs QCD, conversion, harvest, giving, RMD and payment changes through QuantCalc's open tax engines — federal 2.0.0 and state 1.12.0, the same engines behind the federal and state tax APIs — for the 2026 tax year. Each move's effect is the engine's result with the move minus the engine's result without it. The engine documentation lists the official source of every rule; the rules this study leans on:

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments)
• 26 U.S. Code § 86
• 26 U.S. Code § 151
• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments)
• Schedule D (Form 1040) 2025
• 26 U.S. Code § 170
• 26 U.S. Code § 170
• Notice 2025-67: 2026 retirement plan limitations
• 26 U.S. Code § 4974
• 26 U.S. Code § 6654
• 2026 Medicare Parts A & B Premiums and Deductibles
• Rev. Proc. 2025-25: 2026 applicable percentage table (§36B) and required contribution percentage

Labelled assumptions. Federal tax is the return as filed (the Tax Table step below $100,000 of taxable income). IRMAA: 2026 MAGI sets 2028 Medicare premiums; the 2028 tiers are not published, so the 2026 tiers and premiums are used (indexed tiers will be higher, so this can overstate an IRMAA effect but not miss one). ACA: the 2025 poverty line governs 2026 coverage; the benchmark premium is the engine's state-level approximation for the household's ages, all 12 months. State: a joint return is figured on the household's combined income at the filer's age (the state API's household path). Households are illustrations, not averages; the full inputs and the exact API request of every row are in the data files.

An estimate, not tax advice. These are computed examples for the 2026 tax year from QuantCalc's open tax engine (federal 2.0.0, state 1.12.0). Your own return depends on facts these examples do not include. Check any move with your tax preparer or account custodian before acting.

@misc{quantcalc2026whichyearendmovecutsaretirees2026taxmost,
  title  = {Which Year-End Move Cuts a Retiree's 2026 Tax Most? 7 Moves x 12 Households, Federal + State + IRMAA + ACA},
  author = {{QuantCalc Research}},
  year   = {2026},
  url    = {https://quantcalc.app/research/year-end-tax-moves-2026/},
  note   = {Accessed <date>}
}