Year-End Tax Checklist 2026: Answers to the Questions Everyone’s Asking

Tax season feels months away, but the moves that actually lower your 2026 bill have a hard deadline: December 31. Once the calendar flips to January, most of your options disappear. Here are the questions White Buffalo Tax clients ask most this time of year — and straight answers to each one.

What are the 2026 tax brackets and standard deduction?

The standard deduction went up again for 2026: $16,100 for single filers, $32,200 for married couples filing jointly, and $24,150 for head of household. The seven tax brackets (10% through 37%) also shifted higher for inflation, so you can earn a bit more in 2026 before moving into the next bracket. These increases build on changes from the One Big Beautiful Bill Act (OBBBA), which also made the elimination of the old itemized-deduction phase-out permanent — though it now caps how much that benefit is worth if you’re in the top 37% bracket.

How much can I still contribute to my 401(k) and IRA in 2026?

The 2026 401(k) contribution limit is $24,500, up from $23,500 in 2025. If you’re 50 or older, you can add a $8,000 catch-up ($32,500 total) — and if you’re between 60 and 63, your catch-up jumps to $11,250. The IRA limit rose to $7,500, with a $1,100 catch-up for those 50+.

One catch: 401(k) contributions come out of your paycheck, so they have to be set before your last 2026 payroll run — you can’t retroactively fund a 401(k) in January. IRAs are more forgiving; you have until the April 15, 2027 filing deadline to fund a 2026 IRA.

Do I need to make a Q4 estimated tax payment?

If you’re self-employed, freelance, or have income without withholding, yes — your Q4 2026 estimated tax payment is due January 15, 2027, covering income earned September 1 through December 31. Missing it (or underpaying all year) can trigger an underpayment penalty, even if you pay everything owed by April. If your income swung significantly this year, it’s worth recalculating this payment rather than guessing.

What is tax-loss harvesting, and when’s the deadline?

Selling an investment at a loss to offset gains elsewhere — tax-loss harvesting — only counts for 2026 if the trade date is on or before December 31. It doesn’t matter if the trade settles in January. Just watch the wash-sale rule: buying back a substantially identical investment within 30 days before or after the sale disallows the loss entirely.

Do I have to take my RMD by December 31?

If you’re 73 or older, yes — your 2026 required minimum distribution from retirement accounts is due by December 31 (first-timers get until April 1, 2027). Miss it, and the penalty is steep. If you’re 70½ or older and charitably inclined, a Qualified Charitable Distribution (QCD) sent straight from your IRA to a charity can satisfy part of your RMD and avoid a new 2026 rule that limits itemized charitable deductions to the portion above 0.5% of your income.

Can I still make a tax-deductible charitable donation?

Yes, and there’s a new option for 2026: even if you don’t itemize, you can now deduct up to $1,000 in cash gifts ($2,000 if married filing jointly). If you do itemize, remember the new 0.5%-of-income floor mentioned above — and that a mailed check counts on its postmark date, while a card charge counts the day it’s charged, so timing matters if you’re giving right at the wire.

What should I do before my next paycheck in December?

A few quick checks: confirm your 401(k) contributions are on track to hit your target before your final payroll, review whether a Roth conversion makes sense while you can still control which bracket it lands in, and if you pay significant state and local taxes, make sure they’re paid by December 31 to count toward the 2026 SALT cap (now $40,400, phasing down above $505,000 of income).

What’s the single most important year-end tax move?

There isn’t one universal answer — it depends on whether you’re maxing out retirement accounts, managing investment gains and losses, taking an RMD, or just trying to avoid an estimated-tax penalty. That’s exactly why a quick year-end review matters more than any one tip on this list: it catches which of these actually applies to your numbers before the window closes.

Want a second set of eyes on your 2026 tax picture before December 31? White Buffalo Tax offers a free tax return review to help you catch what’s worth acting on now — get yours at whitebuffalotax.com.