Year-End Tax Prep for a Garage Business: A Practical Checklist
The last quarter of the year is a good time to get your garage business’s paperwork in order. A few hours of tidying now can make filing easier in January and help you avoid a surprise tax bill. This is general information, not tax advice, and your situation may differ, so check with a tax professional.
1. Check whether you owe estimated taxes
The IRS says self-employed people, including sole proprietors, generally must make estimated tax payments if they expect to owe $1,000 or more when they file. Because no employer withholds from your business income, you pay Social Security, Medicare and income tax yourself, using Form 1040-ES.
To avoid an underpayment penalty, you generally need to have paid at least 90% of this year’s tax or 100% of last year’s tax, whichever is smaller. Higher earners (2025 adjusted gross income over $150,000) use 110% of last year’s tax instead. The fourth payment for 2026 is due January 15, 2027. According to the Form 1040-ES instructions, you can skip it if you file your 2026 return by February 1, 2027 and pay the full balance with it.
If you have made no payments this year and the numbers look large, don’t panic. Use the worksheet in Form 1040-ES to estimate what you owe, and consider paying what you can by January 15. You can pay online, by phone or through the IRS app. Our guide to garage business taxes explains how self-employment tax works.
2. Bring your books up to date
The IRS says you can use any recordkeeping system that clearly shows your income and expenses. What matters is that you can support every entry on your return. Set aside an hour to catch up on the basics:
- Record every sale, including craft fair cash, marketplace payouts and payments from friends.
- Match your business bank account to your books and note anything unexplained.
- Save receipts for materials, tools, fees, mileage and shipping.
- Put purchase dates and prices on equipment you bought this year.
If you don’t have a system yet, our bookkeeping basics article shows a simple setup. A separate business bank account makes this much easier, and we cover that in getting an EIN and opening a business account.
3. Think through your home office
If you use part of your home regularly and exclusively for business, you may be able to deduct related expenses, whether you own or rent. An extra room or a clearly set-apart section of the garage can qualify. The IRS also offers a simplified option: $5 per square foot of the space, up to 300 square feet, for a maximum of $1,500. (Figures from the IRS as of October 2026.) The deduction can’t exceed the income your business earns from that space.
“Exclusive” is the key word. A garage that also holds the family cars may not qualify for the measured space, so measure and photograph the work area, and keep notes. Our guide on setting up a garage workspace can help you lay it out.
4. Review inventory and equipment
Count your materials and finished goods before the year ends, and write down the totals with the date. Note any tools you bought and when you started using them. A tax professional can tell you how those purchases are treated on your return, because the rules for equipment can be detailed.
5. Plan for filing
Most sole proprietors report business income or loss on Schedule C and calculate self-employment tax on Schedule SE. The IRS notes that you generally must file if your net self-employment earnings are $400 or more. Gather your 1099 forms, marketplace year-end summaries and bank statements in one folder so they’re ready in January.
Also check your state’s rules. Many states have their own income tax, estimated payment dates and sales tax filings. Look at your state revenue department’s website.
A quick year-end checklist
- Estimate your 2026 tax with Form 1040-ES and decide on a payment by January 15, 2027.
- Reconcile your bank and payment-app accounts.
- Sort receipts by category and store copies digitally.
- Measure and document your workspace.
- Count inventory and list equipment purchases.
- Book a short call with a tax professional.
None of this has to be perfect. Starting with one or two steps this week puts you ahead of most new owners, and it makes the next tax season a lot less stressful.
