8 Year-End Tax Moves to Make Before December 31st

Every December, billions of dollars in legal tax savings expire unused. The investment loss you do not harvest, the 401(k) space you do not fill, the charitable bunching you do not plan: all of it closes on December 31 and does not reopen. Tax planning has a hard deadline, and it is not April 15. It is New Year's Eve.

Most people think about taxes in March, when nothing can be changed anymore. The year-end tax moves that actually lower what you owe happen in the last quarter, while there is still time to act.

This post covers the eight moves ranked by typical dollar impact: check where you stand, fill the tax-advantaged buckets, harvest losses, bunch deductions, give strategically, spend down the FSA, take your RMD, and start the paperwork pile.

Move 1: Check Where You Stand

The 20-minute projection

Estimate your 2026 income, deductions, and tax owed versus what has been withheld. A surprise bill in April is worse than a small adjustment now. The income tax calculator runs the projection, and the IRS Tax Withholding Estimator does the same job against your actual paystubs.

If you will owe, increase withholding for the remaining paychecks or make a fourth-quarter estimated payment by January 15, 2027 to avoid underpayment penalties. If you are headed for a big refund, you gave the IRS an interest-free loan, so fix the W-4 for 2027 while you are in there. Our post on how tax brackets work is a quick refresher on marginal versus effective rates.

Know your bracket boundary

Every move below is worth more if it pulls you under a bracket boundary, a credit phaseout, or an IRMAA premium tier. For 2026, the 22% bracket starts at $50,400 of taxable income for single filers and $100,800 for joint filers. Know which side of the line you are on before you decide what a deduction is worth.

Move 2: Fill the Tax-Advantaged Buckets

401(k): use it or lose it

Employee 401(k) contributions must land by December 31. The 2026 limit is $24,500, plus an $8,000 catch-up at 50 and older ($11,250 for ages 60 to 63 under SECURE 2.0), per the IRS announcement of 2026 limits.

You cannot make up employee deferrals in April. Increasing your November and December percentage is the last lever available, and our post on how a 401(k) works covers the mechanics.

IRA and HSA: the April exceptions

IRA contributions ($7,500 plus $1,100 catch-up for 2026) and HSA contributions ($4,400 self-only, $8,750 family, plus $1,000 at 55 and older) can wait until the April 2027 filing deadline. Paying them now still wins, because earlier dollars compound longer. If you are torn between traditional and Roth, our Roth IRA vs traditional IRA breakdown covers the decision, and the HSA tax benefits post explains why the HSA is the most privileged account in the code.

The Roth conversion window

If 2026 income was unusually low (job change, sabbatical, first year of retirement), converting traditional IRA dollars to Roth at a low bracket locks in a cheap tax rate permanently. The conversion has to happen by December 31 to count for 2026. Our post on Roth conversion before retirement covers the timing strategy.

Moves 3 and 4: Harvest Losses and Bunch Deductions

3. Tax-loss harvesting

Sell losers in taxable accounts to offset your gains plus up to $3,000 of ordinary income. Unused losses carry forward indefinitely, so an oversized harvest this year keeps working next year.

The wash-sale rule is the trap: do not buy the same or a substantially identical security within 30 days before or after the sale, in any of your accounts. Buying the repurchase inside your IRA kills the loss permanently, with no carryforward. IRS Topic 409 lays out the netting rules and the $3,000 limit. Our full walkthrough is in the tax-loss harvesting post.

4. Bunch your deductions

The 2026 standard deduction is $16,100 for single filers and $32,200 for married couples, which means most households do not itemize. Bunching concentrates two years of deductible spending into one year so you clear the threshold once instead of falling just short twice.

The moves: pay January's mortgage payment in December, prepay property taxes (the SALT cap is $40,400 for 2026 under the One Big Beautiful Bill Act, far above the old $10,000), pull next year's charitable gifts into December, and schedule deductible medical work before year-end. Then alternate: itemize in bunch years, take the standard deduction in off years. Same generosity, more tax value. Our post on the standard deduction vs itemizing shows the threshold math.

Charitable moves that beat cash

Donate appreciated stock held longer than a year and you deduct the full market value while skipping the capital gains tax entirely. For anyone 70.5 or older, a qualified charitable distribution sends up to $111,000 in 2026 straight from an IRA to charity, counts toward the RMD, and never touches taxable income. For most charitably inclined retirees, the QCD beats the deduction. Our posts on giving to charity without hurting your goals and donor-advised funds cover both strategies.

Moves 5 to 8: Deadlines You Cannot Postpone

5. Spend the FSA

Healthcare FSA money not used by December 31 (or your plan's grace period, or the $680 carryover if your plan offers one) is forfeited. Book the glasses, the dental work, or the prescription refills now while appointments still exist.

6. Take the RMD

Anyone 73 or older (born 1951 through 1959) must take the required minimum distribution by December 31. Missing it costs 25% of the shortfall, reduced to 10% if corrected within two years. First-timers turning 73 in 2026 can delay to April 1, 2027, but that forces two RMDs into one tax year and often costs more than it saves. The IRS RMD FAQ covers the rules, and our post on required minimum distributions walks through the calculation.

7. Check estimated taxes

The fourth-quarter estimated payment is due January 15, 2027. Freelancers, landlords, and anyone with significant untaxed income should top up now rather than settle the penalty later. Our post on self-employed taxes explains the estimated payment system.

8. Start the paperwork pile

January brings W-2s, 1099s, and 1098s. Start the folder now: deductible receipts, charitable acknowledgments, property tax statements, and HSA or FSA records. The tax bracket calculator can confirm which bracket your bunched deductions land you in.

8 Year-End Tax Moves: Deadlines and Typical Impact

Real-World Examples

Example 1: The December harvest

A single filer earning $62,000 holds $4,200 of unrealized losses and $3,800 of realized gains in a taxable account. He harvests the losses in December, zeroing out the gains and deducting the remaining $400 against ordinary income. Tax saved at his marginal rates: roughly $900. He waits 31 days and buys a similar (not identical) index fund, keeping his allocation intact. The sale took 20 minutes and bought nearly a thousand dollars of tax relief.

Example 2: The bunching couple

A married couple has $29,400 of itemizable deductions in a normal year, just under the $32,200 standard deduction. In December 2026 they pull their planned $5,000 charitable gift for 2027 forward and prepay $2,300 of January property tax. Itemized total: $36,700. They itemize in 2026 and take the standard deduction in 2027, capturing about $4,500 of extra deduction worth roughly $990 at the 22% bracket. Same giving, same taxes paid, one calendar trick.

Example 3: The QCD retiree

A 74-year-old with a $31,000 RMD donates $10,000 a year to charity. Routing that gift as a QCD satisfies part of the RMD and removes it from income entirely, saving about $2,200 at the 22% bracket. It also lowers the AGI that drives Medicare IRMAA surcharges and Social Security taxation, so the real savings run higher. For charitably inclined retirees, the QCD is almost always better than the itemized deduction.

Common Mistakes

• Waiting until April. Almost every lever on this list closes December 31. April is just arithmetic.

• Triggering a wash sale. Buying back within 30 days kills the loss, and buying inside an IRA kills it permanently.

• Overpaying the FSA forfeiture. Unspent FSA dollars evaporate. Plan December medical spending around the balance.

• Donating cash while holding appreciated stock. The stock gift double-dips: a full fair-market deduction plus zero capital gains tax.

• Missing the RMD. The 25% penalty is the steepest easily avoided charge in the tax code.

Conclusion

The last quarter is when tax planning actually happens. Check your bracket, fill the 401(k), harvest losses, bunch deductions, spend the FSA, and take the RMD. Each move is small; together they routinely save $1,000 to $3,000 for an average household.

Run your 2026 tax projection this week with our income tax calculator, then pick the two moves from this list that apply to you before December 31.

This post is for informational purposes only and does not constitute tax or financial advice. Consult a qualified tax professional about your specific situation.