Year-End Tax Planning Checklist for High-Income Households

Key takeaways

Start with a projection of the year's income, deductions, and marginal rate; every item below is sized against it.
The largest levers for high earners are retirement plan contributions, charitable gifts of appreciated assets, tax-loss harvesting, and the timing of income across the bracket edges.
Retirees add Roth conversions, RMDs, QCDs, and the IRMAA and Social Security thresholds.
The deadline for almost everything is December 31; the exceptions (IRA, HSA, SEP contributions) are the ones people wrongly assume apply to everything.

Tax planning happens in the fall, not in April. By the time the return is being prepared, every number is locked. The year's income, deductions, contributions, and sales are history. The window to change the outcome runs from about October through December 31, and the items below are what we work through with each client in that window. The order is roughly the order of value for most households.

Start with the projection

Nothing on this list can be sized without an estimate of the year's taxable income, marginal bracket, and position relative to the thresholds that matter: the 24% to 32% bracket edge ($403,550 joint, $201,775 single in 2026), the 0% and 15% capital gains edges ($98,900 and $613,700 joint), the NIIT threshold ($250,000 joint), the QBI phase-in ($403,500 to $553,500 joint), the SALT cap phase-down (above $505,000), the senior deduction phase-out ($150,000 joint), and for anyone 63 or older, the IRMAA tiers ($218,000 joint). The projection tells us how much room there is and which edge is closest. Then we work the list.

Retirement contributions

Max the employer plan. $24,500 in 2026, plus $8,000 catch-up at 50 or $11,250 at ages 60 to 63. Deferrals have to come out of paychecks by December 31; if you're short in November, bump the final deferrals to 100% of pay. Anyone with 2025 FICA wages above $150,000 has to make catch-ups as Roth.
After-tax 401(k) contributions up to the $72,000 total, if the plan allows, for the mega backdoor Roth.
Self-employed plans. Solo 401(k) deferral elections by December 31; the solo 401(k) or SEP employer contribution can follow by the filing deadline. Cash balance plans should be adopted before year-end in practice; the law allows adoption up to the extended filing deadline, but the actuary and administrator need months of lead time.
IRA and HSA contributions can wait until April 15, but the backdoor Roth is cleaner done in the same calendar year, and the HSA ($8,750 family, $4,400 self-only, plus $1,000 at 55) should run through payroll to save FICA.

Charitable giving

Give appreciated securities, not cash, for any gift over a few thousand dollars. The deduction is the full value and the gain never gets taxed. Transfers to charities and donor-advised funds take days to weeks, so start by early December.
Bunch. From 2026, itemizers face a 0.5% of AGI floor on charitable deductions and a 35% cap on the deduction's value for 37% bracket taxpayers. Concentrating two or three years of giving into a donor-advised fund in one year, and taking the standard deduction in the others, is worth more than it used to be. The charitable strategies post has the math.
Qualified charitable distributions for anyone 70½ or older, up to $111,000 per person in 2026, straight from the IRA to charity, satisfying RMDs without touching AGI. The check has to clear by December 31.

Capital gains and losses

Harvest losses in taxable accounts against realized gains and up to $3,000 of ordinary income, with the replacement fund bought the same day and the wash sale rule observed across all accounts.
Harvest gains if the household is under the 0% capital gains edge ($98,900 joint taxable income). Realize gains up to the edge at no tax and reset the basis.
Check fund distributions. Mutual funds announce capital gains distributions in November and pay in December. A fund about to distribute a large gain in a taxable account can sometimes be sold before the record date.
Defer or accelerate sales around the NIIT and bracket thresholds. A sale split across December and January can stay under both.

Income timing

Bonuses and deferred compensation. Elections for next year's deferrals get made now, and a bonus that can be paid in January instead of December moves income into a lower year when the projection shows one.
Roth conversions, sized to fill the current bracket for retirees and pre-retirees, executed in December once the numbers are firm. Our bracket management post covers the sizing; the Roth conversion post covers the strategy. Conversions can't be undone, so we don't rush them.
RMDs have to be taken by December 31 (April 1 of the following year for the first one only), from each 401(k) separately and from IRAs in aggregate. The penalty for a missed RMD is 25% of the shortfall, reduced to 10% if you fix it promptly.
Equity compensation. ISO exercises sized to the AMT crossover; a disqualifying sale of ISO shares bought earlier this year if the stock has dropped; NSO exercises and RSU sales placed in whichever year has room.

Deductions

Itemize or not. The standard deduction is $32,200 joint, $16,100 single in 2026. With the SALT cap at $40,400 (phasing down above $505,000 of MAGI), more high-income households itemize than in recent years. The projection tells us which year to bunch deductions into.
State and local taxes. Where the cap has room, paying the January property tax installment in December may help, subject to the phase-down.
Medical expenses above 7.5% of AGI, mainly relevant in years of big long-term care costs.
The senior deduction. $6,000 per person 65 or older, phasing out above $150,000 of joint MAGI. A conversion or gain that pushes MAGI past the phase-out costs you the deduction on top of the tax.

Gifts and estate

Annual exclusion gifts of $19,000 per recipient have to be completed by December 31, and checks have to clear. The gifting post covers what to give.
529 contributions with the five-year election for grandparents.
Review beneficiary designations while the accounts are open anyway. This is the boring one. Do it.

Retirees, specifically

Everything above, plus the tax torpedo range for Social Security, the IRMAA tiers two years out, the ACA subsidy cliff for anyone under 65, and withholding. Retirees can substitute IRA withholding for quarterly estimates, and a December withholding on an RMD counts as paid evenly through the year, which cures an underpayment penalty that estimates can't.

Payments

Fourth-quarter estimated payments are due January 15. Withholding and estimates should reach 110% of last year's tax (for AGI above $150,000) or 90% of this year's, whichever is less, to avoid the underpayment penalty. In a year with a large event, a December withholding adjustment or an IRA withholding is the cleanest fix.

How we run it

Every client's projection gets updated in October with the year's actual income and the fall's known items, and we work the list above against it in a single meeting, with the trades, transfers, and elections done by early December. That's the core of what tax planning means here. Not the return. The decisions before the return exists.

Frequently asked questions

Can I still reduce my tax bill after December 31?

Only through IRA, HSA, and SEP contributions and, for the self-employed, the employer side of a solo 401(k). Everything else is fixed at year-end.

Should I prepay next year's charitable gifts?

If you're near the standard deduction, yes, into a donor-advised fund, so the bunched year itemizes and the next year takes the standard deduction.

What if I do not know my income yet?

A projection with ranges is still enough to act on the items that are clearly right (harvesting losses, maxing the 401(k), gifting appreciated stock) and to hold the ones that hinge on the final number (conversions, gain harvesting) until mid-December.

Do you prepare my return?

No. We plan and project, and we send the year's planning summary to whoever prepares the return so the two line up.

Joseph G. Valerio, CFP®, EAFounder and Lead Advisor at Valerio Wealth Management, a fee-only, fiduciary virtual family office in Miami, Florida. One advisor, credentialed in both financial planning and federal tax. About Joseph

This article is general education, not individualized advice, and it is not tax, legal, or accounting advice. Figures reflect federal law for the year stated and can change. Valerio Wealth Management does not prepare or file tax returns. Speak with a qualified professional about your own situation before acting.