Year-End Tax Planning Checklist for Small Businesses (2026 Edition)

Why Q4 Is the Most Important Time of Year for Business Taxes

Most small business owners think about taxes in March and April — when it's too late to change anything. The decisions that actually reduce your tax bill are made in October, November, and December, while you still have time to act. This checklist covers the essential year-end planning moves every small business owner should review before December 31.

1. Review Your Estimated Tax Position

Calculate your projected taxable income for the full year and compare it to what you've paid in estimated taxes. If you're significantly behind on estimates, consider making a catch-up payment before year-end to avoid underpayment penalties. If you've overpaid, that's working capital you could be using in the business — adjust your Q4 estimate accordingly.

2. Accelerate Deductible Expenses Before December 31

If you're on a cash basis (most small businesses are), expenses are deductible in the year you pay them — not when the bill arrives. Consider prepaying deductible expenses before December 31: rent, professional services, supplies, insurance premiums, and any other ordinary and necessary business expenses you'll incur early in the following year anyway.

3. Maximize Retirement Contributions

Contributions to a SEP-IRA, SIMPLE IRA, or Solo 401(k) reduce your taxable income directly. SEP-IRA contributions can be made as late as your tax return due date (including extensions), but SIMPLE IRA and 401(k) salary deferrals must be elected before December 31. If you haven't maxed out your retirement contributions for the year, this is often the highest-value tax planning move available to small business owners.

4. Evaluate Equipment and Asset Purchases Under Section 179

Section 179 allows you to immediately deduct the full purchase price of qualifying equipment and business property in the year of purchase, rather than depreciating it over several years. Bonus depreciation provides similar benefits for new and used qualified property. If you're planning equipment purchases for early next year, consider whether it makes sense to accelerate the purchase into the current year to capture the deduction.

5. Review Your Business Structure

Year-end is a good time to confirm that your current business structure (sole proprietorship, LLC, S-Corp, C-Corp) is still optimal for your tax situation. S-Corp elections made by March 15 can be effective for the following tax year. If your net income has grown significantly, an S-Corp election may reduce self-employment taxes on your earnings — but this analysis depends on your specific facts and should be done with your CPA.

6. Don't Forget State and Local Tax Obligations

Texas has no state income tax, which is a significant advantage for San Antonio business owners. But if you have business activity in other states, you may have income tax filing obligations in those states. Review your business activities outside Texas and confirm you're meeting all out-of-state filing requirements. State nexus rules have expanded significantly in recent years, particularly for online and remote businesses.

7. Gather Documentation for Deductible Expenses

Year-end is also the time to ensure you have adequate documentation for all deductions you plan to take. This includes receipts for business meals (must include business purpose and who attended), mileage logs if you're deducting vehicle expenses, documentation for home office deductions, and charitable contribution receipts. The IRS disallows deductions that can't be substantiated — no matter how legitimate the expense.