Contractor Tax Deductions: What You Can Write Off in 2026

Common Tax Deductions Every Contractor Should Claim

The IRS allows construction contractors to deduct any expense that is "ordinary and necessary" for running the business. The challenge isn't knowing what's deductible — it's making sure your bookkeeping system actually captures and categorizes everything correctly. Here are the deductions contractors miss most often.

Vehicle and Equipment Expenses

Trucks, trailers, and heavy equipment are the biggest assets most contractors own. You can deduct these through Section 179 accelerated depreciation (up to $1,220,000 in 2026) or standard depreciation schedules. Fuel, maintenance, insurance, and registration are also deductible. Keep a mileage log for vehicles used for both personal and business purposes — the IRS standard mileage rate for 2026 is $0.70/mile.

Materials and Supplies

Every material purchased for a job — lumber, concrete, fasteners, plumbing fixtures, electrical supplies — is deductible as a cost of goods sold (COGS) when properly tied to a specific project. The key is job costing: materials assigned to a project reduce your gross profit on that project. Materials sitting in your warehouse are inventory, not a deduction, until they're used.

Subcontractor Payments

Payments to subcontractors are deductible business expenses. File a 1099-NEC for every sub paid $600 or more during the year. Missing 1099s can trigger IRS penalties of $310 per form (2026 rate). Track these in QuickBooks by vendor with their W-9 on file before the first payment.

Insurance Premiums

General liability, workers' comp, commercial auto, builder's risk, professional liability, and umbrella policies are all deductible. For contractors, insurance is often 3–8% of revenue. Make sure premiums are categorized as overhead (not job cost) unless a policy is project-specific like builder's risk on a spec build.

Home Office Deduction

If you run your business from a dedicated home office, you can deduct a proportional share of mortgage/rent, utilities, insurance, and maintenance. The simplified method allows $5 per square foot up to 300 sq ft ($1,500 max). The regular method tracks actual expenses. Many contractors skip this because they think it triggers audits — it doesn't, as long as the space is used exclusively for business.

Retirement Plan Contributions

SEP-IRAs allow contributions up to 25% of net self-employment income (max $69,000 for 2026). Solo 401(k) plans allow even more if you're the only employee. These reduce your taxable income dollar-for-dollar and are one of the most powerful deductions available to profitable contractors.

Deductions Contractors Miss Most Often

In our experience working with contractors in the $500K–$10M range, the most commonly missed deductions fall into a few categories.

Change Orders That Were Never Invoiced

This isn't a deduction — it's the opposite. When approved change orders don't get billed, you've done the work, spent the money, and paid taxes on phantom profit you never collected. Our average client recovers $28,400 in unbilled change orders in the first 60 days. That's not a deduction — it's found revenue.

Tools and Small Equipment

Tools under $2,500 can be expensed immediately rather than depreciated. Many contractors buy tools on personal cards or with cash and never record the purchase. A simple system: photograph every receipt, categorize it in QuickBooks the same day, and assign it to a job if it's project-specific.

Professional Development and Licensing

Contractor licensing fees, continuing education, trade association memberships (NAHB, AGC, local HBA), industry conferences, and trade publications are all deductible. These add up to $2,000–$5,000 per year for most contractors.

Job-Site Travel and Per Diem

Travel to job sites beyond your normal commute is deductible. If you're working a project out of town, hotel, meals (50% deductible), and transportation are business expenses. The IRS per diem rate for construction workers simplifies this — no need to save every meal receipt if you use the standard rate.

How to Make Sure You're Catching Everything

The real problem isn't knowing what's deductible. It's having a bookkeeping system that actually captures it. Here's what we recommend for every contractor.

Use the NAHB Chart of Accounts. It separates direct job costs from overhead, which is the only way to know your true gross profit margin — and the only way to ensure every expense is categorized correctly for tax purposes.

Job cost every expense. Every material purchase, sub payment, and equipment rental should be tied to a specific project. Expenses that aren't job-costed get dumped into overhead and often get miscategorized.

Reconcile weekly, not monthly. The longer you wait, the more receipts disappear and the more expenses get missed. A 30-minute weekly reconciliation in QuickBooks catches problems before they become tax-season scrambles.

Work with someone who knows construction. A generalist bookkeeper categorizes expenses. A construction fractional CFO job-costs them, tracks them by phase, and makes sure your tax preparer has clean data to work with.