Self-employment tax: you pay both halves

Self-employment tax is why freelancers panic in April. Six figures on paper. Half vanishes to taxes.

This is not financial advice. Understanding SE tax is the difference between managing money and drowning in surprises. Here's the exact math.

What SE tax is

SE tax is Social Security and Medicare combined.

As employee: 6.2% (SS) + 1.45% (Medicare) = 7.65%. Your employer matched it. You saw your half. Theirs was invisible.

Self-employed: you pay both. 12.4% + 2.9% = 15.3% of net SE income.

SS tax (12.4%) caps at $168,600 income (2024). Medicare (2.9%) has no cap. Every dollar after $168,600 still gets hit with 2.9%.

The formula

Pay SE tax on net income (gross minus business expenses), not gross.

Net SE income × 0.9235 × 15.3% = SE tax.

Example: $60,000 net income.

• $60,000 × 0.9235 = $55,410
• $55,410 × 0.153 = $8,478 SE tax

Deduction matters, but it's not a credit. You pay full 15.3%. The deduction just lowers other tax liability.

Quarterly taxes (required)

IRS expects payment as you earn, not once per year.

If you'll owe $1,000+ per year, you must pay quarterly.

• Q1 (Jan-Mar): April 15
• Q2 (Apr-Jun): June 15
• Q3 (Jul-Sep): September 15
• Q4 (Oct-Dec): January 15 next year

Estimate annual income, calculate tax, divide by four, send each quarter. Don't pay = penalties and interest.

Penalty is ~8% annualized (2024), compounded daily. Not huge, but stacks fast. Miss Q1 and Q2, you pay penalties on that amount for all 12 months.

Safe harbor rule

Avoid penalties if you pay either:

• 100% of last year's tax, OR
• 90% of this year's tax

Higher earner? (Last year AGI over $150k?) Safe harbor is 110% of last year, not 100%.

For job-to-freelance switchers: Year 1, use last year's employment tax as your safe harbor. Conservative estimate, avoid penalties. Year 2+, nail current-year numbers or face penalties.

Real example

You quit January 1. Last year was W-2 at $75k.

Year 1: bill $100k gross. Net $85k after business expenses.

SE tax: $85,000 × 0.9235 × 0.153 = $12,008.

Federal income tax (single, estimated): $18,000.

Total federal: $30,008.

$100k gross billings nets $85k. After federal tax, you have $55k to spend. That's 45% effective tax rate (SE + federal).

Most people budget 25-30% total tax. That's the shock.

Add state tax on top

CA, NY, MA add 8-12% more. In California, that $85k person faces total tax rates near 50%.

That's why you need 12 months of runway. One year covers the tax hit and living expenses.

One tool: HSA

High-deductible health plan? Max your HSA. Triple tax advantage: deductible going in, grows tax-free, withdrawals for medical are tax-free. Best tax shelter most people don't use.

Solo 401k: another option. Up to $69k/year (2024) pre-tax. Requires more paperwork than HSA.