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Several tax moves have a hard December 31, 2026 deadline, including 401(k) contributions, tax-loss harvesting, required minimum distributions, and FSA spending, while IRA and HSA contributions actually have until the April 2027 tax filing deadline. Mixing these up is the most common year-end tax mistake. Here’s what needs to happen by December 31 and what can wait.
Key Takeaways
- 401(k) contributions, tax-loss harvesting, RMDs, and FSA spending must happen by December 31, 2026.
- IRA and HSA contributions have until April 2027, the tax filing deadline, not December 31.
- The 2026 QCD limit is $111,000 per person, up from $108,000 in 2025, and it can satisfy your RMD.
- Health FSA carryover into 2027 is capped at $680; anything above that is forfeited unless your plan has a grace period instead.
What Actually Has a December 31 Deadline?
- 401(k), 403(b), and 457 elective deferrals: these come out of paychecks, so your last chance to adjust them is your final paycheck of the year, not December 31 itself. Check your remaining pay dates now if you’re trying to hit the max.
- Tax-loss harvesting: trades must settle by the market’s last trading day of the year to count for 2026. See our full tax-loss harvesting guide for how to avoid the wash-sale rule.
- Required minimum distributions (RMDs): due by December 31 for most retirees already taking them (the one exception is your very first RMD year, which can be delayed to April 1). Missing it carries a real penalty. See our RMDs explained guide.
- Qualified charitable distributions (QCDs): if you’re 70½ or older, you can send up to $111,000 directly from your IRA to charity in 2026, and it counts toward your RMD without adding to taxable income.
- Charitable donations for a 2026 deduction: checks, card charges, and stock transfers all need to be completed, not just initiated, by December 31.
- Health FSA spending: use-it-or-lose-it funds need to be spent by year-end unless your employer offers a $680 carryover or a grace period, not both. See our HSA vs. FSA guide for the difference.
What Actually Has Until April 2027?
Two of the most common accounts people rush in December don’t need to be: Traditional and Roth IRA contributions and HSA contributions can both be made up until the 2026 tax filing deadline in April 2027, not December 31. There’s no rush to fund these before New Year’s, though doing it earlier does give the money more time to grow. If you’re weighing a Roth conversion instead of a straight contribution, that decision does need to happen by December 31, since conversions are locked to the calendar year. See our year-end Roth conversion guide.
What About the New OBBBA Deductions?
Several new deductions from the 2025 tax law (OBBBA) apply for the first time on 2026 returns, including a new above-the-line charitable deduction for people who don’t itemize. Check whether your year-end giving plan can take advantage of it before you finalize donations. Full breakdown in our OBBBA tax changes guide and 2026 tax brackets and standard deduction guide.
A Quick Pre-December 31 Checklist
- Check your last few 2026 paychecks to see if you can still hit your 401(k) target.
- Review your brokerage account for losing positions worth harvesting before the market closes for the year.
- Confirm you’ve taken your full RMD if you’re required to, or set up a QCD if you’d rather give than withdraw.
- Check your FSA balance and spend down anything above your plan’s carryover limit.
- Finish any charitable giving you want counted for 2026, and confirm it actually clears by December 31.
- Leave IRA and HSA contributions for later if you need the cash flow now, you have until April 2027.
FAQ
What tax moves have to happen by December 31?
401(k) elective deferrals (via your last paychecks), tax-loss harvesting trades, required minimum distributions, qualified charitable distributions, charitable donations you want deducted for 2026, and FSA spending.
Do IRA contributions have to be made by December 31?
No. Traditional and Roth IRA contributions for the 2026 tax year can be made up until the April 2027 filing deadline.
What happens to unused FSA money?
It’s forfeited at year-end unless your employer offers a carryover (up to $680 for 2026) or a grace period of about two and a half months, plans can offer one or the other, not both.
What is the 2026 QCD limit?
$111,000 per person, up from $108,000 in 2025. A QCD sends money directly from your IRA to charity and can satisfy your RMD without counting as taxable income.
Bottom Line
The real December 31 deadlines are 401(k) contributions, tax-loss harvesting, RMDs, and FSA spending, while IRA and HSA contributions can wait until April 2027. Work through the checklist above in the next few weeks so nothing time-sensitive slips past the new year.
A quick note: this guide is here to help you plan your own year-end moves, not to act as personal tax advice. Rules and limits come from the IRS and can change, so it’s worth confirming your specific numbers with a tax professional or at irs.gov before you act.
