Side Hustle Tax Calculator

When you earn income from a side hustle (freelancing, gig work, selling online, tutoring, content creation), that income is subject to both income tax and self-employment tax, which catches many new side hustlers completely off guard.

Key formulas: Net Self-Employment Income = Gross Side Hustle Revenue − Business Expenses Self-Employment Tax = Net SE Income × 0.9235 × 15.3% SE Tax Deduction = SE Tax × 50% (deducted from gross income) Taxable Income = Net SE Income − SE Tax Deduction − Other Deductions Total Federal Tax = Income Tax on Taxable Income + SE Tax Recommended Quarterly Payment = Total Expected Federal Tax ÷ 4

What each variable means:

• Self-Employment Tax: you pay both the employee and employer share of Social Security (12.4%) and Medicare (2.9%) = 15.3% combined. The 0.9235 multiplier accounts for the deductible half.
• SE Tax Deduction: the IRS allows you to deduct half of your SE tax from gross income, slightly reducing your income tax.
• Quarterly Estimated Taxes: if you expect to owe $1,000+ in federal taxes from self-employment, you must pay quarterly (April 15, June 15, September 15, January 15) to avoid underpayment penalties.

Deductible business expenses (reduces taxable SE income):

• Home office (proportional square footage)
• Equipment, tools, software
• Professional subscriptions
• Business portion of phone/internet
• Mileage at IRS rate ($0.67/mile in 2024)
• Health insurance premiums (self-employed deduction)

Worked example: Side hustle gross income: $18,000. Business expenses: $2,500. Net SE income = $15,500. SE Tax = $15,500 × 0.9235 × 0.153 = $2,189 SE deduction = $2,189 × 0.5 = $1,095 If in the 22% federal bracket: Additional income tax ≈ ($15,500 − $1,095) × 0.22 = $3,169. Total additional tax = $2,189 + $3,169 = $5,358. Set aside roughly 30–33% of gross income.