Year-end money moves: the December 31 deadline checklist

The tax year slams shut at midnight on December 31, and with it a surprising number of doors: contribution deadlines, spending deadlines, harvesting windows, and distribution requirements. April's filing deadline gets all the attention, but by then most of the levers are welded in place — the return just reports what December decided. The good news: the year-end list is short, most items take minutes, and running it in the first week of December leaves time for the ones that need processing.

The hard December 31 deadlines

The checklist, in priority order

1. Check your 401(k) year-to-date against the limit (~$24,500, 2026 estimate). Under-contributed and can afford more? Raise the final paycheck deferrals now — payroll needs lead time.
2. Spend the dying FSA: glasses, contacts, dental work, prescription refills, and a surprising catalog of eligible items. Check whether your plan has a grace period or small carryover before panic-shopping.
3. Harvest losses in taxable accounts: sell losers to offset gains plus up to $3,000 of ordinary income, and mind the 30-day wash-sale rule on rebuying.
4. Batch charitable giving if you itemize — or 'bunch' two years of gifts into one via a donor-advised fund to clear the standard deduction hurdle. Over 70½? Ask about qualified charitable distributions from an IRA.
5. Low-income year? Consider a Roth conversion to fill the 10–12% brackets — a recession-year layoff or sabbatical is a conversion opportunity wearing a disguise.
6. Take any required minimum distributions — the penalty for missing is brutal and the December custodian backlog is real.
7. Sweep the admin: use expiring rewards points and airline credits, spend down expiring gift cards, and confirm your final estimated tax payment if you're self-employed (due mid-January).

What not to do in December

Year-end urgency sells bad products. Beware the December pitch for whole life insurance or annuities 'for the tax benefits,' last-minute crypto or hot-stock moves justified as tax plays, and buying anything primarily because it's deductible — spending $1,000 to save $220 is still losing $780. The checklist above is about timing decisions you'd make anyway, not manufacturing new ones. If a December move requires a salesperson, it can wait until January, which usually means forever, which is usually correct.

The bottom line

December 31 is the real tax deadline — April just does the paperwork. Run the list in the first week of December: top up the 401(k), drain the FSA, harvest the losses, batch the giving, take the RMDs, and consider a conversion in a low year. Two hours, a short list of clicks, and typically hundreds to thousands of dollars that simply don't exist in January. Few rituals pay better than closing out the year on purpose.

The worked December: one household's checklist run

Here is the checklist executed by a composite dual-income household in the first two weeks of December — the realistic version, where not every line applies and the whole exercise takes about three hours across two evenings (estimates; tax figures illustrative, not advice).

Two thousand dollars for three December hours, and every line came from deadlines that quietly expire at midnight on the 31st — the match does not retroactively fill, the FSA money vanishes, the loss-harvest and deduction windows close with the tax year. The FSA line is the most commonly missed in real life: hundreds of dollars forfeit annually per affected household (est.), usually because nobody checked the balance until January. The fix is embarrassingly simple: check the balance December 1, and remember that FSA-eligible spending is broader than people think — glasses, contacts, first-aid supplies, and many over-the-counter items count.

Common mistakes of deadline season

The first is starting December 28: brokerages, HR portals, and charities all process in business days, and trades need settlement time — moves initiated in the final week routinely miss the deadline they were racing. Run the checklist the first week of December and the deadlines become comfortable. The second is harvesting losses and immediately rebuying the identical security, which triggers the wash-sale rule and voids the loss; wait the required window or buy a similar-but-not-identical replacement. The third is letting the checklist expand into a full financial overhaul at the year's most crowded moment — December is for deadline-bound moves only, and the IRA contribution (deadline: tax day) and the insurance re-shop (deadline: none) belong on January's calendar, where they will get done instead of skipped. Deadline triage is the whole December skill.