California tax filing: file California state taxes online, FTB Form 540, deadlines and requirements

Do you have to file a California tax return?

California decides this with income thresholds that depend on your filing status, your age, and how many dependents you claim. You are required to file if you clear either the gross income threshold or the adjusted gross income threshold, whichever you hit first. Gross income is everything you received before deductions; California AGI is your federal AGI with state adjustments applied.

These are the tax year 2025 gross income thresholds, the ones filed in 2026:

The adjusted gross income thresholds sit lower, which is why some people who clear neither number on paper still end up with a filing requirement. For 2025, a single filer or head of household under 65 must file at California AGI of 18,353 with no dependents, 34,186 with one, and 46,061 with two or more. Married couples filing jointly or separately, both under 65, hit those points at 36,711, 52,544 and 64,419.

Reasons to file even when you are under the threshold

• Withholding on your paychecks. If California tax came out of your W-2 all year and you owe nothing, the only way to get it back is to file.
• Refundable credits. The California Earned Income Tax Credit and the Young Child Tax Credit can pay out even with little or no tax liability, and both require a filed return.
• Self-employment income. Independent contractors reporting on Schedule C often clear the threshold on gross receipts alone, before a single expense comes off.

The full requirement tables are published by the Franchise Tax Board and update every year with inflation.

Form 540, Form 540 2EZ or Form 540NR

California has one personal income tax return with three faces, and picking the wrong one is the most common cause of a rejected or amended filing.

1. Form 540, California Resident Income Tax Return. The standard return for anyone who lived in California all year. It handles itemized deductions, the full credit list, and every income type the state taxes.
2. Form 540 2EZ. A simplified alternative for straightforward resident returns. Less to fill in, but it restricts which income types, deductions and credits you can report, so it is not always the cheaper option in real dollars.
3. Form 540NR. The combined nonresident and part-year resident return. If you moved into or out of California during the year, or you lived elsewhere but earned California-source income, this is your form. There is no separate part-year version.

Residency drives all of it, and California applies a facts-and-circumstances test rather than a simple day count: where your home is, where your family lives, where your car is registered, where you vote. People who split the year between California and a no-income-tax state are the ones the FTB looks at hardest, so keep dated records of the move.

Filing electronically is the practical default. Paper returns to the FTB take considerably longer to process and refunds follow the same pace. If you want the mechanics of e-filing in general, the online tax filing walkthrough covers what happens between upload and acceptance, and the state tax filing pillar compares how the states differ from each other.

California tax filing deadline and the automatic extension

California's extension works differently from the federal one, and the difference is worth understanding. There is no form to file and no application to submit. Every individual filer gets an automatic six-month extension to file, granted by default, which moves the paperwork deadline to October 15, 2026. You do not request it, you do not get approved for it, and there is nothing to attach to the eventual return.

What the extension does not do is delay payment. If you expect to owe, the money is due April 15, 2026, and interest plus a late-payment penalty run from that date on anything unpaid. If you are paying by mail, the voucher is FTB 3519, which exists only to accompany that payment. Filers who owe nothing or expect a refund can ignore the voucher entirely and simply file by October.

The federal side is not automatic in the same way, so do not assume one covers the other. Our guide to filing a federal tax extension explains Form 4868 and the separate IRS rules, and when taxes are due lays out the full 2026 calendar including quarterly estimated payments, which extensions never postpone.

California tax rates, brackets and the standard deduction

California is a graduated-rate state, not a flat one. Rates on the 2025 schedule run from 1.00% to 12.30% across nine brackets, and only the income inside each band is taxed at that band's rate. The top 12.3% bracket begins at 742,953 dollars of taxable income for single filers and 1,485,906 dollars for married couples filing jointly.

Above one million dollars of taxable income there is an additional 1% charge. For tax years beginning on or after January 1, 2025 this was renamed the Behavioral Health Services Tax, replacing the former Mental Health Services Tax name, and it is reported on Form 540 line 62. Combined with the top bracket it produces the effective top marginal rate of 13.3% you see quoted in national coverage.

The California standard deduction is far smaller than the federal one, which is why itemizing on the state return sometimes makes sense even when you took the federal standard deduction:

California also departs from federal treatment in places that catch filers out: it does not conform to every federal deduction, it taxes some income the IRS leaves alone, and it applies exemption credits rather than personal exemptions. Current rate schedules are posted on ftb.ca.gov. If you want a rough sense of where your federal return lands before you start, the tax refund calculator gives you a quick estimate.

Filing your California return online with TaxFile

The practical problem with California filing is duplication. The state return draws on federal figures, so preparing them in two places means entering the same W-2 twice and reconciling any difference yourself. TaxFile builds both from one pass.

• Upload or talk. Drop in your W-2s and 1099s and it reads them, or describe your year in plain language and it asks what it still needs.
• Federal and California prepared together. One set of documents produces both returns, with the California figures carried through consistently.
• Deductions and credits checked. It looks for what you qualify for and explains each item rather than leaving you to hunt through a credit list.
• Error check before anything moves. Inconsistencies get flagged so they are fixed before submission, not after a rejection notice.
• You approve, then it files. E-filing happens through an authorized IRS e-file provider only after you have reviewed and approved every line. It never files silently.

Pricing is 39 dollars for a simple return, 89 for self-employed, 199 for business, plus 19 for each state return. There is no free tier. If your California income comes from contract or freelance work, self-employed tax filing covers the Schedule C and Schedule SE side of the return in more detail.

Two limits worth stating plainly. TaxFile does not e-file Form 4868 federal extensions and does not prepare amended returns, and it does not currently handle capital gains on Schedule D, rental income on Schedule E, or cryptocurrency transactions. If your year includes any of those, a CPA is the right call. TaxFile is self-prepared tax software and does not provide personalized tax, legal or accounting advice, and no refund or refund amount is ever guaranteed.