Year-End Money Moves: Which Deadlines Are Real, and Which Can Wait

Year-end financial advice usually arrives as a long list of things to do by December 31. The list is not wrong, but it buries the one distinction that decides whether you still have time: some moves must happen inside the calendar year, and some get until the following April. People who miss that split either miss the December moves entirely or rush contributions that had months left to run.

Here is the map, sorted by deadline rather than by importance.

December 31: the moves that expire with the year

These cannot be done retroactively. If the year closes with them undone, the opportunity is gone.

Employer retirement plan deferrals. Contributions to a 401(k), 403(b) or 457 plan come out of payroll, so the money has to be withheld from a paycheck before the year ends. Looking at your year-to-date deferral in November is the whole exercise — if you are behind on maxing it out, ask payroll whether an extra deduction from the last paycheck or two is possible. Many plans also allow a “true-up” match that corrects for uneven contributions; some do not, so check rather than assume.

Roth conversions. Moving money from a traditional IRA to a Roth is a taxable event in the year it happens, and the conversion must be completed — not just requested — by December 31. This is where the ordering advice matters: convert in the fall, when your income for the year is nearly knowable, not in the last week of December.

Realized gains and losses. Tax-loss harvesting — selling a position at a loss to offset realized gains, and up to $3,000 of ordinary income against excess losses, with the rest carried forward — is a calendar-year transaction. So is deliberately realizing a gain in a year when it will be taxed at a low rate. Two mechanics matter:

• The wash-sale rule disallows the loss if you buy a substantially identical security within 30 days before or after the sale — in any account, including an IRA. Buying a similar but not identical fund keeps your market exposure while preserving the loss.
• Gains have no wash-sale rule. That asymmetric detail is what makes tax-gain harvesting work for people in the 0% long-term capital gains bracket: sell the appreciated position, recognize the gain at zero, and step up your basis.

Also watch fund distributions in November and December. Buying a mutual fund just before a capital gains distribution means receiving a taxable distribution for gains you never participated in. If you are making a purchase in December, check the distribution date first.

Required minimum distributions. If you are subject to RMDs, the withdrawal must be taken by December 31 — the first year has a limited delay option, but after that there is no grace period. Note the age rules changed under SECURE 2.0: since 2023 the required beginning date is 73, and for those born in 1960 or later it is 75. The penalty for missing one is 25% of the amount that should have been withdrawn, reduced to 10% if corrected promptly within the statutory window. RMDs cannot be satisfied by Roth conversions, and the amount is calculated per account even where aggregation is permitted.

Charitable gifts. Cash gifts must be received by the charity by December 31. Gifts to a donor-advised fund count when the fund receives them, which is one reason DAFs are popular in December — you get the deduction this year and choose the actual charities later. Donating appreciated stock rather than cash is usually the better move when you have a position with a large gain: the charity receives the full value, you deduct it, and no one pays the capital gain. Also check the current deduction rules before you plan around them — Congress changed the treatment of charitable deductions for recent tax years, and the thresholds and floors are not what they were.

Bunching. If your itemized deductions hover near the standard deduction, concentrating two years of giving into one year can push you over the line in that year and take the standard deduction in the other. The technique only works if the year is planned in advance — which is to say, now.

Annual exclusion gifts. The per-recipient gift tax exclusion applies to gifts made during the calendar year, and does not carry over. Married couples can combine their exclusions for a single recipient.

Business owners: placing equipment in service by December 31 is what makes it eligible for the year’s depreciation treatment, and retirement plans, entity elections and cost-segregation studies generally take weeks to arrange — so December is already late for those. Cash-basis businesses also decide here whether to accelerate income and defer expenses, or the reverse, based on which year will be the higher-income one.

April: the moves that have months left

Two contributions for the tax year can generally be made up to the filing deadline in the following April:

• IRA contributions, including for a backdoor Roth strategy — though doing the contribution and the conversion in the same calendar year keeps the paperwork tidy and avoids a second Form 8606 straddling two years.
• Health savings account contributions, if you had a qualifying high-deductible health plan.

Neither needs to be rushed into December, and neither should be forgotten. The HSA is the only account that is tax-deductible going in, grows tax-free, and comes out tax-free for qualified medical expenses — which makes it the most tax-advantaged account available to most people, and the most underused.

Plan-dependent: flexible spending accounts are usually use-it-or-lose-it, though many employers allow a small carryover or a short grace period. That is a plan document question, not a tax question — check it before the money evaporates, and check it in October or November rather than on December 30.

The deadline that costs money quietly: MAGI

Here is the part that is not on the year-end posters.

Your modified adjusted gross income for this year drives costs in later years, and two of the levers are on this page:

• Medicare premiums. Part B and Part D premiums use MAGI from two years earlier to determine income-related surcharges. A large Roth conversion or realized gain this December can raise your premiums two years out, at thresholds that are fixed for the year and that a single dollar over the line can trigger for the whole household.
• Marketplace subsidies. If anyone in the household has ACA coverage, MAGI also determines premium tax credit eligibility, and a spike can move you across the income line that changes your subsidy. Our insurance site covers the mechanics of that cutoff in The ACA Subsidy Cliff Is Back.

So the order of operations at year end is: project your income first, then choose the transactions. A Roth conversion or a loss-harvesting trade is not a good decision in isolation — it is a decision about a specific number, and separately about the year that follows the lookback.

Two more dates belong on the calendar. If you pay estimated taxes, the fourth-quarter payment is due in mid-January, and sizing it is part of the same projection. And the Social Security COLA announced in October changes next year’s income, which is why it belongs in the same planning conversation — our walkthrough of that is in The 2027 Social Security COLA.

One caution on the numbers themselves: contribution limits, bracket thresholds, income-related premium tiers and the charitable rules are indexed and adjusted most years. Confirm the current figures for your tax year with the IRS before calculating anything — an article, including this one, is a map of the decisions, not a table of the amounts.

The short version

• By December 31: payroll deferrals, Roth conversions, realized gains and losses, RMDs, cash charitable gifts, annual exclusion gifts, assets placed in service.
• By the filing deadline in April: IRA and HSA contributions for the year.
• Check your plan document: FSA carryover, grace period, true-up matching.
• Before any large transaction: model the MAGI effect on Medicare premiums two years out and on any ACA subsidy.
• Then: spend December executing a plan made in the fall, not improvising one.

The moves with a hard deadline are the ones that reward looking early. Everything on the April list rewards patience — but only if the December list has already been handled.