Year-end tax planning checklist for founders

By the time you file your return, the year is over and most of your options are gone. Q4 is when you can still change the outcome. Here’s the checklist.

1. Know where the year is landing

Close the books through September or October and project the rest of the year. Every other decision on this list depends on a realistic estimate of profit.

2. Make your Q4 estimated payment plan

The Q4 federal estimate is due January 15. If the year went better than expected, pay enough to avoid an underpayment penalty.

3. Time big purchases

If you need equipment, computers, or vehicles for the business, buying and placing them in service before December 31 can pull the deduction into this year. The 2025 tax law brought back 100% bonus depreciation for qualifying property, and Section 179 expensing is also available. Don’t buy things you don’t need just for a deduction, though.

4. Look at retirement contributions

Retirement plans are one of the biggest deductions available to founders. Some plans have to be set up before year-end, while others can be opened and funded up to your filing deadline. Figure out which applies before December.

5. Check S-corp payroll

If you’re an S-corp, make sure you’ve paid yourself a reasonable salary through payroll by year-end. You can’t fix that after the fact.

6. Revisit your entity

If profit has grown a lot this year, check whether an S-corp election makes sense for next year. If you’re raising venture money, check whether a C-corp conversion should be on the table.

7. Clean up the books

Uncategorized transactions, unreconciled accounts, and missing receipts are much easier to fix in December than in March.

The short version

Project the year, plan the Q4 payment, time real purchases, sort out retirement and payroll, and clean up the books. Talk to us before December, not after.