How to File California State Taxes: Forms, Deadlines, and Payment

To file California state taxes, complete your federal return first, choose the California form that matches your residency (Form 540 for residents, 540 2EZ for simple resident returns, or 540NR for part-year residents and nonresidents), make any California-specific adjustments on Schedule CA, and submit by April 15, 2026 through the Franchise Tax Board’s free CalFile system, commercial tax software, or by mail. Payment is also due April 15, even if you use the automatic six-month extension to finish the paperwork.

Finish Your Federal Return First

California’s income tax return starts where your federal return ends. Form 540 asks you to carry over your federal adjusted gross income and then apply California-specific adjustments, so you need a completed Form 1040 or 1040-SR in hand before you begin.¹ Your California filing status generally has to match your federal filing status too, which is another reason to settle the federal return first.

Enter your name and address on the state return exactly as they appear on the federal one. Round every dollar amount to the nearest whole dollar.²

Pick the Right Form

California has three main personal income tax forms. Using the wrong one gets your return bounced back.

Form 540 is the standard return for full-year California residents. It handles every income type, deduction, and credit.
Form 540 2EZ is a simplified version for residents with straightforward tax situations. You can use it if your total income is $100,000 or less (single or head of household) or $200,000 or less (married filing jointly), you’re claiming no more than three dependents, and your income comes from wages, interest, dividends, pensions, or unemployment.³
Form 540NR is required for part-year residents and nonresidents. It allocates your income between California and non-California sources so you’re taxed only on what California can claim.

Residency drives the form choice. A full-year resident is someone in California for other than a temporary purpose, or someone domiciled in California who is temporarily elsewhere.⁴ Residents are taxed on all income wherever earned. A part-year resident moved into or out of the state during the year. A nonresident lives outside California but earned California-source income, such as wages from a California employer or rent from California property; only that California income is taxed.

Even if your income falls below the filing thresholds published in the Form 540 instructions, file anyway if California withheld tax from your paycheck or you qualify for a refundable credit like the CalEITC. You can’t get a refund without a return.¹

Documents to Gather

Before you sit down with the form, pull together:

Social Security numbers for you, your spouse, and any dependents
Your completed federal Form 1040 or 1040-SR
W-2s from every employer, showing wages and state withholding
1099 forms for interest (1099-INT), dividends (1099-DIV), retirement distributions (1099-R), unemployment (1099-G), and any other income
Proof of health coverage for each month of the year (Form 1095-A, 1095-B, or 1095-C)
Records of out-of-state purchases where California sales tax wasn’t collected, if you owe use tax

California Adjustments Most People Miss

California doesn’t conform to every federal tax rule, so you may need to adjust your federal AGI using Schedule CA (540). Skipping this step is one of the more common filer mistakes. The adjustments that trip people up most often:

Health Savings Accounts. California doesn’t recognize HSAs. Any federal HSA deduction gets added back, and employer contributions are taxable for California purposes.⁵
Out-of-state municipal bond interest. California taxes interest from bonds issued by other states and their municipalities, even though federal law exempts municipal bond interest.
529-to-Roth IRA rollovers. Federal law now allows tax-free rollovers from 529 plans to Roth IRAs under certain conditions. California taxes the rollover as income and adds a 2.5% penalty.⁵
Net operating losses. For tax years beginning on or after January 1, 2024, and before January 1, 2027, California has suspended the NOL carryover deduction. Any NOL claimed federally has to be added back for California.
Gambling losses. Federal law caps gambling loss deductions at the amount of gambling winnings. California doesn’t follow that limitation.

The full adjustment list runs several pages. If you have any income source beyond simple W-2 wages, read the Schedule CA instructions before assuming your federal numbers carry straight over.

Standard Deduction and Credits

The 2025 standard deduction is $5,706 for single and married-filing-separately filers, and $11,412 for married couples filing jointly, heads of household, and qualifying surviving spouses.⁶ These are well below federal levels, so some filers who take the federal standard deduction do better itemizing on California.

Two refundable credits are worth checking before you finish:

The California Earned Income Tax Credit (CalEITC) is worth up to $3,756 for the 2025 tax year if your earned income is $32,900 or less.⁷
The Young Child Tax Credit adds up to $1,189 per return for families with a qualifying child under six, if you also qualify for CalEITC.⁸

Other credits include the renter’s credit, the child and dependent care expenses credit, and a credit for taxes paid to another state on income California also taxes.

Report Your Health Coverage

California has its own individual healthcare mandate. On your 2025 return you must report whether every member of your household had qualifying coverage for each month of the year. Anyone who went without coverage and doesn’t qualify for an exemption owes a penalty.⁹

The penalty is the higher of a flat amount or 2.5% of household income above the filing threshold. For 2025, the flat amount is $950 per uninsured adult and $475 per uninsured child. A family of four earning under $177,163 would pay roughly $2,850 under the flat calculation if nobody had coverage all year.⁹ Common exemptions include income below the filing threshold, a short coverage gap of three consecutive months or less, and unaffordable coverage. Some exemptions are claimed on your return using Form FTB 3853; others require a certificate from Covered California.

How to File

Electronic Filing

CalFile is the FTB’s free e-file system for preparing and submitting your state return through the FTB website.¹⁰ It works for most residents with relatively simple returns. Your federal AGI has to be under $252,203 (single), $378,310 (head of household), or $504,411 (married filing jointly).¹¹ CalFile isn’t available if you have capital gains or losses, business income (Schedule C), rental income (Schedule E), or HSA deductions.

Third-party tax software also e-files California returns, usually bundled with your federal filing. Some products charge a separate fee for the state return.

Paper Filing

If you mail your return, the address depends on whether you owe:

Refund or no balance due: Franchise Tax Board, PO Box 942840, Sacramento CA 94240-0001
Payment enclosed: Franchise Tax Board, PO Box 942867, Sacramento CA 94267-0001¹²

Pay by April 15, Even If You File Later

Your 2025 return and any balance due are both due April 15, 2026.¹³ California grants every individual an automatic six-month filing extension to October 15, 2026, with no application required.¹⁴

The extension covers paperwork only. Money owed is still due April 15. Estimate what you owe and pay by that date to avoid penalties and interest. If you’re mailing a payment while taking the extension, use Form FTB 3519. Web Pay lets you pay directly from a checking or savings account at no cost.¹⁵ Credit card payments carry a service fee. If you owe nothing, you don’t need to do anything before October 15.¹⁴

Your return also has a line for use tax on out-of-state purchases where California sales tax wasn’t collected. For personal items under $1,000 each, you can use a lookup table based on AGI instead of tracking receipts.

Penalties If You’re Late

Filing and payment penalties stack.

Late filing: 5% of the unpaid tax per month or partial month, up to 25%. If your balance is $540 or less, the minimum penalty is $135 or 100% of the amount due, whichever is less.¹⁶
Late payment: 5% of the unpaid tax initially, plus 0.5% for each additional month, up to 40 months.¹⁶
Interest: 7% per year on unpaid balances through June 30, 2026.¹⁷
Demand penalty: if the FTB sends you a demand to file and you don’t, an additional 25% penalty applies to the entire balance.

Individuals who owe $500 or more and don’t pay electronically also face a 1% noncompliance penalty. The takeaway: the automatic extension protects you from the filing penalty, but pay by April 15 to protect yourself from the payment penalty and interest.

Track Your Refund

The FTB’s “Where’s My Refund?” tool at ftb.ca.gov shows your refund status. You’ll need your Social Security number, ZIP code, the exact refund amount, and the numbers from your mailing address.¹⁸

Current FTB processing runs about three weeks for e-filed returns and four weeks for paper. Refunds take roughly one month for e-file and up to four months for paper.¹⁹ E-file with direct deposit is the fastest combination. If the FTB flags something for review, expect longer waits and watch your mail for notices asking for more information.

1
Franchise Tax Board. 2025 Instructions for Form 540 California Resident Income Tax Return
2
Franchise Tax Board. 2024 Instructions for Form 540 Personal Income Tax Booklet
3
California Franchise Tax Board. 2024 Form 540 2EZ Personal Income Tax Booklet
4
California Legislative Information. California Revenue and Taxation Code 17014 – Resident
5
Franchise Tax Board. 2025 Instructions for Schedule CA (540) California Adjustments – Residents
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Franchise Tax Board. Deductions
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Franchise Tax Board. California Earned Income Tax Credit
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Franchise Tax Board. Young Child Tax Credit
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Franchise Tax Board. Health Care Mandate – Personal
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Franchise Tax Board. CalFile
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Franchise Tax Board. CalFile Qualifications 2025
12
Franchise Tax Board. Mailing Addresses
13
Franchise Tax Board. Due Dates: Personal
14
Franchise Tax Board. Extension to File
15
Franchise Tax Board. Pay by Bank Account (Web Pay)
16
Franchise Tax Board. Common Penalties and Fees
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Franchise Tax Board. Interest and Estimate Penalty Rates
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Franchise Tax Board. Where’s My Refund?
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Franchise Tax Board. Timeframes – Wait Times