Most tax-saving moves stop working on December 31. This is the checklist we walk through with every client in November — each item takes under 30 minutes but can save thousands.
By the time April rolls around, most tax-saving levers are already locked. The window to actually move the needle is October through December. Here are the ten moves we prioritize.
1. Max out retirement contributions
401(k) and 403(b) contributions must be withheld from a paycheck dated by December 31. Call payroll now if you're behind. 2026 limits:
- 401(k): $24,000 ($31,500 if 50+)
- IRA: $7,500 ($8,500 if 50+) — you have until April 15 for IRA contributions, but earlier is better
- HSA: $4,400 single / $8,750 family ($1,000 catch-up if 55+)
2. Harvest investment losses
If you have losing positions in a taxable brokerage account, consider selling to realize the loss. You can offset unlimited gains, plus up to $3,000 of ordinary income. Watch the wash-sale rule: don't rebuy the same or substantially identical security within 30 days.
3. Consider a Roth conversion
If your taxable income is lower than usual this year (between jobs, sabbatical, early retirement before Social Security), a Roth conversion can lock in a low tax rate on amounts you'd eventually be forced to take out anyway. Must happen by December 31.
4. Bunch charitable deductions
The standard deduction is high enough ($30,000 MFJ, $15,000 single in 2026) that many charitable givers no longer itemize. The workaround: bunch two or three years of giving into one year to clear the standard deduction. A donor-advised fund is the easiest vehicle.
5. QCDs — if you're over 70½
If you're over 70½ and have an IRA, you can send up to $108,000 directly from your IRA to charity — it counts toward your RMD and isn't included in your income. Often better than writing a check from your bank account.
6. For business owners: buy needed equipment
Section 179 and bonus depreciation let you fully expense most business equipment, vehicles, and software in the year placed in service. If you were going to buy it in January anyway, buying in late December can save thousands. But: don't buy junk just for the deduction — the savings is at most your marginal rate.
7. For business owners: run final payroll with bonuses
S-Corp owners: if you've under-paid yourself salary relative to your distributions, December is the time to catch up with a year-end bonus (through payroll). You can also fund your SEP-IRA or Solo 401(k) employer contribution based on final payroll numbers.
8. Review withholding and safe harbor
You avoid underpayment penalties if you paid in either (a) 90% of this year's tax or (b) 100% of last year's tax (110% if AGI over $150K). If you're short, you can still catch up by increasing W-2 withholding in the last paycheck (withholding is treated as evenly paid all year — estimated payments aren't).
9. 529 contributions
Missouri offers a state income tax deduction of up to $8,000 per person ($16,000 for a married couple) for contributions to a MOST 529 plan. Contributions must post by December 31. Check your own state's deduction rules if elsewhere.
10. Gather documents now
Not a tax move, but a sanity one. Make a folder (digital or physical) and start dropping in:
- Any tax documents received in January (W-2, 1099, 1098, K-1)
- Closing documents if you bought or sold a home
- Summary of quarterly estimates paid
- Medical, property tax, and charitable giving totals
- For businesses: year-end P&L and balance sheet
- For foreign-account holders: year-end balances for every account
The difference between a client who pays what they owe and a client who overpays is almost always what happened in Q4.
Want us to walk you through this list personally? We do year-end planning calls with every client between mid-October and mid-December. Get in touch and we'll put you on the calendar.