Once December 31 passes, most of the choices that shape your 2026 tax bill are locked in. The last quarter of the year is when planning actually pays off. Here is the checklist we walk through with clients every fall.
For everyone
1. Run a projection before you do anything else
Take your income so far, add a reasonable estimate for the rest of the year and see where you land. You can't decide whether to push income into next year or pull deductions into this one until you know which tax bracket you're in.
2. Max out retirement contributions
For 2026, the employee deferral limit for 401(k), 403(b) and most 457 plans is $24,500, with an extra $8,000 for those 50 and older and $11,250 for those 60 through 63. IRA contributions top out at $7,500 plus a $1,100 catch-up. Deferrals through payroll generally have to happen by December 31, while IRA contributions can wait until the filing deadline. See our full 2026 limits guide.
3. Rethink charitable giving
New rules start in 2026. Non-itemizers can deduct some cash gifts again, and itemizers face a new floor. Read what changed for charitable giving before you write year-end checks.
4. Look at your investment gains and losses
If you have realized gains, consider whether selling positions with losses makes sense to offset them. Watch the wash-sale rule if you plan to buy back the same investment.
5. Check your withholding and estimated payments
If you had a big income change this year, a quick W-4 adjustment or a fourth-quarter estimated payment (due January 15, 2027 for most individuals) can prevent an underpayment penalty.
6. Use it or lose it: FSA balances
Many flexible spending accounts have a December 31 deadline or a short grace period. Check your plan.
For business owners
7. Time big purchases
Equipment, vehicles and software placed in service by December 31 may be deductible this year under Section 179 or bonus depreciation. Our year-end business deductions guide covers the current rules.
8. Review your salary if you're an S corporation owner
Owner-employees of S corporations should be paid reasonable compensation through payroll. Year-end is the time to check that your salary is defensible and that payroll reflects it before W-2s go out.
9. Clean up your books now, not in March
Reconcile every bank and credit card account through November, and chase any missing receipts. Clean books make every other item on this list easier.
10. Get ready for 1099 season
Collect W-9s from every contractor you paid this year. The reporting threshold for 2026 payments rose to $2,000; see our 1099 changes article.
11. Consider cash vs. accrual timing
If you're on the cash method, you may be able to pay some January expenses in December or delay billing until January. Make sure it makes sense for cash flow, not just taxes.
12. Revisit your entity structure
If your business grew a lot this year, it may be worth asking whether your current structure still fits. Changes often need to be made early in the next year, so start the conversation now.
A note on Oregon
Oregon generally follows federal rules for many items but does not conform to everything. Some federal changes, particularly around depreciation, can be treated differently on your Oregon return. We review both sides for our clients.
This article is general information, current as of September 2026, and is not tax, legal or financial advice for your situation. Tax rules change often. Talk with us before acting on anything here.