Result
How to use this calculator
Enter each deduction you can document: home office square footage, business miles driven, the business share of phone and internet, self-employed health insurance premiums, and retirement plan contributions. The calculator totals your business expenses and above-the-line adjustments, then estimates the tax they save at your marginal rate.
The formula
Business expenses (home office at $5/sq ft up to 300 sq ft, mileage at the IRS standard rate, phone/internet business share) reduce your net profit. Above-the-line items (half of SE tax, SE health insurance, retirement contributions) reduce your adjusted gross income. Estimated savings = total deductions × your marginal tax rate.
2026 reference rates
Standard mileage rate: 76 cents per mile for business miles driven on or after July 1, 2026; miles driven Jan-Jun 2026 use 72.5 cents. Home office simplified method: $5 per square foot, capped at 300 square feet. Verify both with the IRS each January — they change.
FAQ
What can I deduct as a self-employed person?
Ordinary and necessary business costs: home office, mileage, phone and internet business share, software, supplies, health insurance premiums, half of your SE tax, and retirement contributions — each with its own IRS rules.
How does the home office deduction work?
The simplified method gives you $5 per square foot of regularly and exclusively used workspace, capped at 300 square feet ($1,500 maximum). The actual-expense method may yield more but requires recordkeeping.
Is the mileage rate the same every year?
No. The IRS adjusts it annually — 2026 is a split-rate year: 72.5 cents per business mile Jan-Jun and 76 cents from July 1 (IRS Announcement 2026-11). This tool applies the current 76-cent rate; use the mileage calculator to split the year exactly.
Which deductions reduce SE tax?
Only business expenses do, because they shrink net profit before the SE tax is computed. Health insurance and retirement contributions are income-tax deductions but do not reduce SE tax.