Tax season reveals the same pattern every year: business owners who could have saved thousands in taxes simply didn't know about deductions they were entitled to claim. Here are five of the most commonly missed opportunities.
1. Home Office Deduction
If you use a dedicated space in your home regularly and exclusively for business, you can deduct a portion of your rent or mortgage, utilities, insurance, and maintenance. The simplified method allows $5 per square foot up to 300 square feet ($1,500 maximum), while the regular method calculates the actual percentage of your home used for business.
2. Vehicle Expenses
Business use of your personal vehicle is deductible, but many owners fail to track their mileage consistently. The standard mileage rate for 2026 is 67 cents per mile. A simple mileage tracking app can document thousands of dollars in deductions over the course of a year.
3. Retirement Plan Contributions
SEP-IRAs allow you to contribute up to 25% of net self-employment income (up to $69,000 for 2026). Solo 401(k) plans offer even more flexibility with both employee and employer contribution components. These contributions reduce your taxable income dollar for dollar.
4. Health Insurance Premiums
Self-employed individuals can deduct 100% of health insurance premiums for themselves, their spouse, and dependents. This is an above-the-line deduction, meaning you don't need to itemize to claim it.
5. Professional Development
Courses, certifications, conferences, books, and subscriptions related to your business are deductible. This includes industry conferences, online courses, professional association memberships, and trade publications.
The Bottom Line
Proactive tax planning with a CPA who understands your business ensures you're capturing every legitimate deduction. If you're preparing your own returns or working with a generalist, you may be paying more than you need to.