Year-end tax planning is not glamorous, but the moves you make before December 31 can meaningfully reduce what you owe when you file. This checklist covers 12 concrete actions for 2026 — from retirement contributions to withholding adjustments — each tied to specific dollar amounts and deadlines.
1. Max Your 401(k) Contributions
The 2026 employee elective deferral limit is $23,500 ($31,000 if 50+, $34,750 if 60–63). Every pre-tax dollar contributed reduces your taxable income now. If you have not hit the limit, increase your deferral rate with your HR or benefits portal before the final payroll of the year. Contributions must come through payroll — you cannot make a lump-sum 401(k) contribution after year-end. See our 2026 401(k) limits guide for full details.
2. Fund Your HSA
If you have a qualifying HDHP, the projected 2026 HSA limit is $4,400 (self-only) or $8,750 (family). HSA contributions are deductible, grow tax-free, and withdraw tax-free for medical expenses — the only triple-tax-advantaged account. You have until April 15, 2027, to contribute for 2026 if contributing directly (not through payroll). See our 2026 HSA limits guide.
3. Review Your W-4 Withholding
A major life change in 2026 — marriage, divorce, a new child, a side income, or a significant pay increase — can cause under-withholding and a surprise balance due at filing. Use our payroll tax calculator to estimate your year-end position. If you are under-withheld, you can file a new W-4 with your employer to increase withholding for the remaining pay periods, or make a Q4 estimated tax payment by January 15, 2027.
4. Harvest Tax Losses
If you hold investments with unrealized losses in a taxable brokerage account, selling them before December 31 lets you realize the loss and offset capital gains — or offset up to $3,000 of ordinary income if losses exceed gains. This is called tax-loss harvesting. Be aware of the 30-day wash-sale rule: you cannot repurchase the same or substantially identical security within 30 days before or after the sale and still claim the loss.
5. Check Your Capital Gains Exposure
Long-term capital gains are taxed at 0%, 15%, or 20% depending on your income. If your income for 2026 will be below the 15% threshold (~$47,025 single / ~$94,050 MFJ projected), you may be able to realize long-term gains at a 0% rate. Conversely, if you plan to sell appreciated assets, doing so before your income crosses a threshold can save meaningful tax. See our 2026 capital gains rates guide.
6. Make Your Q4 Estimated Tax Payment
If you are self-employed, have rental income, or receive significant investment income, your Q4 2026 estimated tax payment is due January 15, 2027. To avoid underpayment penalties, your total payments (withholding + estimated) must cover at least 90% of your 2026 tax or 100% of your 2025 tax (110% if 2025 AGI exceeded $150,000). See our quarterly estimated tax guide.
7. Bunch Charitable Contributions
With the 2026 standard deduction projected at ~$15,750 (single) or ~$31,500 (MFJ), most filers take the standard deduction and get no marginal benefit from charitable donations. Consider bunching two years of donations into 2026 to push above the standard deduction threshold, then skip 2027. A donor-advised fund (DAF) lets you contribute a lump sum in 2026, claim the full deduction, and distribute gifts to charities over multiple years.
8. Take Required Minimum Distributions (RMDs)
If you are 73 or older and have traditional IRA or pre-tax 401(k) balances, you must take your 2026 RMD by December 31. Missing an RMD triggers a 25% penalty on the amount not taken (reduced to 10% if corrected promptly). First-year RMDs for those who turned 73 in 2026 can be delayed until April 1, 2027 — but delaying means two RMDs in 2027, which can push income higher.
9. Consider a Roth Conversion
If your 2026 taxable income is lower than usual — due to retirement, a sabbatical, or a business loss — this may be a good year to convert some pre-tax IRA funds to Roth. The conversion amount is added to your taxable income, so the goal is to convert up to the top of your current bracket without crossing into the next. Roth accounts have no RMDs and grow tax-free indefinitely. See our Roth conversion tax guide.
10. Review Your MAGI for Key Thresholds
Several deductions and credits phase out at specific MAGI thresholds. Check where you stand before year-end so you can take action if you are close to a limit:
- Child Tax Credit ($2,200/child): phases out at $200,000 single / $400,000 MFJ
- Roth IRA direct contributions: phase out $150,000–$165,000 single / $236,000–$246,000 MFJ (projected)
- Traditional IRA deductibility: phases out at lower thresholds if covered by a workplace plan
- Net Investment Income Tax (3.8%): applies above $200,000 single / $250,000 MFJ
- Additional Medicare surtax (0.9%): same thresholds as NIIT
Pre-tax retirement contributions (401k, traditional IRA, SEP-IRA) reduce MAGI and can shift you below a threshold. An end-of-year calculation now gives you time to act.
11. Use Flexible Spending Account Balances
Healthcare FSA and Dependent Care FSA balances typically follow use-it-or-lose-it rules, though many plans offer a small grace period or rollover. Check your FSA balance now — if you have money you might not use, schedule medical appointments, order prescription refills, pick up eligible OTC items (bandages, pain relievers, etc.), or buy prescription eyeglasses before the plan year closes.
12. Start Gathering Records for Filing
Begin organizing documents now so you are ready for the April 15, 2027 filing deadline. Key items to track: all W-2s and 1099s, brokerage year-end statements (for cost basis), records of charitable contributions, home office or vehicle business use logs, and any 1095-A if you received ACA marketplace coverage. If you use a tax professional, book early — capacity fills up in February and March.
Important 2026 Tax Deadlines to Know
Use our income tax calculator to estimate where you stand now, then revisit after making any of these moves to see the impact on your projected tax bill.