Free U.S. Tax Calculators for Freelancers & 1099s

Private tax calculators for freelancers, 1099 contractors, and independent workers. Check your limits, avoid IRS penalties, and keep your numbers private—nothing leaves your browser.

✓ Instant Results

✓ 100% Private in Browser

✓ No Sign-Up Required

✓ 2025 & 2026 Tax Years

Tax Planning & Estimation Tools

Choose a calculator below to get your numbers.

IRS Form 8889 · IRC § 223

When do you need this?

You have an HSA and want to find your exact contribution limit—for the full year or with mid-year plan changes.

HSA Contribution Limit & Testing Period Calculator

Find your exact HSA contribution limit, check if you qualify for the full-year December rule, and see how mid-year coverage changes affect your taxes.

Best for: Anyone with an HSA, especially if you changed jobs, tiers, or started coverage after January 1st.

Month-by-month plannerFull-year December rulePenalty simulatorPaycheck breakdown

Launch HSA Calculator

IRS Form 1040-ES · IRC § 6654

When do you need this?

You earned freelance, contractor, or side income without automatic tax withholding.

1099 Safe Harbor Tax Calculator

Calculate how much you need to pay each quarter to avoid IRS underpayment penalties. Compare prior-year vs. current-year safe harbors and adjust for W-2 withholding.

Best for: Freelancers, 1099 contractors, and employees with side income or freelance earnings.

90% vs 100%/110% comparisonW-2 withholding adjustmentMissed-quarter penalty estimatePrintable payment vouchers

Launch Safe Harbor Calculator

Why SoloTaxKit

Your Data Stays on Your Device

We don't ask for your name, email, or bank login. All calculations run directly in your browser. You can even disconnect your internet and the calculators will keep working.

Built on Official IRS Rules

Every formula follows IRS guidelines and annual inflation updates for 2025 and 2026 (IRC § 223 and § 6654), calculated to the exact penny so you can file with confidence.