California Self-Employment Tax: A 2026 Filing Guide for Freelancers

A note on the tax year. Everything below comes from California's published tax year 2025 rate table — the most recent the FTB has released. The installment dates belong to the 2026 installment year. California has not released a 2026 tax-year rate table yet; this page will be updated when it does.

Does California have a state income tax?

Yes. California levies a personal income tax on residents, and it taxes nonresidents on the income they source to California. Self-employed filers report net business profit on Form 540 — the same return wage earners use — so a freelancer's California return is an ordinary personal income tax return with a business schedule attached.

Where a California obligation comes from depends on two things:

• Residency. If California is your home state, your income is generally taxable and you file a California return.
• California-source income. If you live elsewhere but earn from California, only the income sourced to the state is taxable — work you physically performed in California, or services tied to a California business.

For a freelancer, the second path is the one that creeps up. Remote work makes it easy to create California-source income without noticing, and the sourcing question — where the work was actually done — usually decides it, not the client's mailing address.

Comparing states? The state tax hub covers all five in this cluster.

California income tax rate for self-employed filers

For tax year 2025, California's top marginal rate is 12.3%. That top bracket starts at $742,953 of taxable income for single filers and married-filing-separately filers (Schedule X), $1,485,906 for married filing jointly and qualifying surviving spouse (Schedule Y), and $1,010,417 for head of household (Schedule Z).

On top of the ordinary brackets, California applies a 1% surtax — the Behavioral Health Services Tax — to taxable income over $1,000,000. Because that 1% sits on top of whatever bracket rate already applies, the combined marginal rate above $1,000,000 depends on your filing status:

• Single / married filing separately (Schedule X): the 12.3% bracket already begins at $742,953, so every dollar above $1,000,000 is taxed at 12.3% + 1% = 13.3%.
• Married filing jointly / qualifying surviving spouse (Schedule Y): the 12.3% bracket does not begin until $1,485,906, so from $1,000,000 up to $1,485,906 the marginal rate is 11.3% + 1% = 12.3%; the combined 13.3% rate begins only above $1,485,906.
• Head of household (Schedule Z): the 12.3% bracket begins at $1,010,417, so from $1,000,000 up to $1,010,417 the marginal rate is 11.3% + 1% = 12.3%; the combined 13.3% rate begins only above $1,010,417.

In short: 13.3% is a single-filer number at the $1,000,000 line. Joint and head-of-household filers reach 13.3% later, at their own 12.3% thresholds.

Use the current name. For tax years beginning on or after January 1, 2025, California renamed what it had long called the "Mental Health Services Tax." The FTB states it directly:

If a guide or calculator still labels that 1% surtax the "Mental Health Services Tax," it is working from an outdated name.

A reminder: 12.3% and 13.3% are marginal rates — they apply only to your last dollars, not to your whole income. The lower brackets do the work up to that point.

A quick example. Devon, a San Diego copywriter, expects to owe about $600 in California tax. Crossing the $500 line is enough to trigger four installments — not one April payment — and the third is $0. Miss the split and the penalty surfaces at filing time.

When you have to file and when you must prepay

Two separate thresholds decide your obligations: the income line at which you must file, and the tax line at which you must start paying in installments.

Whether you must file. California uses a gross-income test that shifts with your filing status, age, and number of dependents. For the common case — a single or head-of-household filer under 65 with no dependents — you must file once gross income exceeds $22,941. That same filer must also file if California adjusted gross income exceeds $18,353. Because the threshold moves with your filing status, age, and dependents, treat those numbers as an example and confirm your own line on the FTB's "Do I Have to File?" table.

When you must prepay. California requires estimated tax payments once you expect to owe at least $500 in state tax for the year — $250 if you file married filing separately. The safe harbor is paying 90% of your current-year liability through withholding and estimated payments; fall short and you risk an underpayment penalty. California does not divide its four installments evenly: the required fractions are 30% / 40% / 0% / 30%. The third installment is genuinely zero, which trips up filers who assume four equal quarters.

If you operate through an entity. Two business-level charges can sit alongside your personal tax. A California LLC owes an $800 annual minimum franchise tax, and an S-corporation faces a 1.5% entity-level tax with the same $800 minimum. These are separate from the individual income tax; see our LLC for freelancers guide for how they factor into the entity decision. If you file as a sole proprietor, the Schedule C filing guide covers the profit-and-loss side.

If you are still mapping the federal layer, start with the self-employment tax guide, then come back to the California rules above it.

California estimated tax due dates

For the 2026 installment year, California's four estimated tax payments are due:

• April 15, 2026
• June 15, 2026
• September 15, 2026
• January 15, 2027

Your 2025 California return is due April 15, 2026, with an automatic extension to October 15, 2026. An extension to file is not an extension to pay — the tax is still due in April, and late payment accrues interest.

Because California's split is uneven, the installments are not simply "a quarter each time." The quarterly estimated tax guide walks through how to size each payment, and the self-employment tax calculator runs the numbers against your own income.

Local taxes

This page covers state-level taxes only. It does not cover any city, county, or district tax that may apply to you — verify locally. California's verified local layer here is San Francisco: a business with gross receipts allocated to the city above $500,000 must register with the San Francisco Office of the Treasurer & Tax Collector, and one with combined taxable San Francisco gross receipts above $5,000,000 must file a gross receipts (GR) tax return. Local business taxes in California vary widely by jurisdiction, so treat this as a starting point, not a complete local review.

Where these numbers come from

• California Franchise Tax Board — 2025 Form 540 booklet — tax rate schedules (p.75), the Behavioral Health Services Tax and its 2025 rename (p.16), filing thresholds (p.4), and estimated tax rules (p.3, p.9)
• California Franchise Tax Board — estimated tax payments — the $500 prepayment trigger and the 90% safe harbor
• California Franchise Tax Board — Limited Liability Company — the $800 annual minimum tax
• California Franchise Tax Board — Form 1123 — the 1.5% S-corporation tax
• SF Office of the Treasurer & Tax Collector — register a business — the $500,000 registration threshold
• SF Office of the Treasurer & Tax Collector — gross receipts tax — the $5,000,000 GR filing threshold

Tax year 2025 for rates and thresholds; 2026 for installment due dates. California's 2026 tax-year rate table is not yet published. Last verified September 2026.