tax-timing Audience: general 4 min read

Year-End Tax Checklist: Moves to Make Before December 31

Don't wait until April. The most impactful tax moves have a hard deadline of December 31. Use this checklist to lock in savings.

In the world of tax, the calendar is your boss. Some moves (like IRA contributions) can be done until April 15. But the heavy hitters — 401(k)s, Roth Conversions, Loss Harvesting — must be done by December 31. Once the ball drops in Times Square, your tax year is cemented.

Key Takeaways

  • Roth Conversions must be finalized by 12/31.
  • 401(k) / 403(b) deferrals must be made through payroll by year-end.
  • Tax Loss Harvesting trades must execute (and settle) in the tax year.
  • Charitable gifts (checks mailed / credit cards charged) must happen by 12/31.

The “Must Do” List (Deadline 12/31)

1. Harvest Losses

Look at your brokerage account. Anything down? Sell it to bank the loss. Buy a replacement ETF to stay invested. (Watch out for the wash sale rule.) You can offset unlimited capital gains and up to $3,000 of ordinary income per year. See our full tax loss harvesting guide for a step-by-step walkthrough.

2. Roth Conversions

If you are having a low-income year (gap year, business loss), convert Traditional IRA to Roth to fill up your low tax brackets. The math on Traditional vs. Roth depends entirely on your marginal rate today versus retirement. For a multi-year approach, see the Roth conversion ladder strategy.

3. Required Minimum Distributions (RMDs)

If you are over age 73 (or inherited an IRA), you MUST take your RMD. The penalty for missing it is effectively 25%. Don’t mess this up.

4. Max Out 401(k) / 403(b) Contributions

Check your year-to-date payroll deferrals. The 2026 limit is $24,500 (under 50), $32,500 (50+), or $35,750 (ages 60-63 under SECURE 2.0). If you are behind, increase your deferral percentage for the remaining paychecks. See our direct 401(k) contribution strategies for more.

5. Charitable Bunching

If you are close to the itemizing threshold, make that big donation now. Use a Donor Advised Fund to bunch multiple years of giving into one. (See: Charitable Bunching). Retirees 70½+ can also make Qualified Charitable Distributions directly from an IRA.

6. FSA Clean Out

Check your Flexible Spending Account balance. Use it or lose it. Buy glasses, endless sunscreen, or a fancy first-aid kit.

7. Max Out Your HSA

HSA contributions can technically wait until April 15, but if you are contributing through payroll deductions, make sure you are on track to hit the limit ($4,400 self / $8,750 family for 2026). The HSA triple tax advantage makes this one of the most powerful accounts available.

The “Can Wait” List (Deadline 4/15)

Keep Up with Estimated Payments

If you are self-employed, remember that the Q4 estimated tax payment is due January 15. It is easy to forget this one in the holiday rush. Missing it can trigger underpayment penalties.

Focus on the December deadlines first.

How sharper.tax Helps

sharper.tax analyzes your uploaded return and builds a personalized year-end checklist — flagging which strategies (Roth conversions, tax loss harvesting, charitable bunching, retirement contributions) would move the needle for your specific tax situation. We show your effective tax rate alongside peers so you can see how much room there is to improve. Sophisticated tax planning used to require a high-end CPA — we make it available for free.

Sources

The information above is educational and not tax advice.