How to File Taxes in California

Who has to file a California return

California residents required to file a federal return are generally also required to file a California return. Part-year residents and nonresidents with California-source income — from a job, rental property, or business based in the state — are generally required to file as well.

Filing thresholds are based on filing status, age, and gross or adjusted gross income, and are published each filing season by the FTB. The thresholds are indexed for inflation, so the exact dollar figures shift slightly from year to year, and a taxpayer whose income falls under the threshold may still choose to file in order to claim a refund of withheld state tax or a refundable credit such as CalEITC.

Residency status determines what income is taxed

California taxes full-year residents on all income regardless of where it was earned, including income from another state. Part-year residents are taxed on all income earned while a California resident, plus any California-source income earned during the nonresident portion of the year. Nonresidents are taxed only on income sourced to California, such as wages for work physically performed in the state or income from a California-based business or property.

The FTB applies a facts-and-circumstances test to determine residency, weighing factors such as where a taxpayer's home, family, and principal place of business are located, and where they are registered to vote or hold a driver's license. A person physically present in California for more than nine months of the tax year is presumed to be a resident, though this presumption can be rebutted with sufficient documentation.

How California taxes differ from the federal return

California starts from federal adjusted gross income and applies its own additions and subtractions, since the state does not conform to every federal tax rule. Differences include the treatment of certain retirement account contributions, HSA contributions (California does not recognize the federal HSA deduction), and some business deductions. These differences are reconciled on Schedule CA (540), which adjusts the federal AGI figure up or down before arriving at California taxable income.

California runs its own bracket structure, separate from federal brackets, with rates from 1% up to 12.3%, plus the additional 1% surtax over $1 million, for an effective top marginal rate of 13.3%. California does not apply a separate, lower rate to long-term capital gains — gains are taxed as ordinary income, which means the tax on investment gains can be materially higher in California than at the federal level for higher earners.

• No preferential rate for long-term capital gains — taxed as ordinary income
• HSA and some retirement contributions are treated differently than on the federal return
• No tax on Social Security benefits
• Separate state standard deduction and exemption amounts from the federal ones
• Unemployment compensation is exempt from California tax, unlike at the federal level

Filing methods

Filing starts from the completed federal return, since Form 540 uses federal AGI as its starting point. The FTB accepts several filing channels, and most taxpayers who e-file their federal return can e-file their California return through the same software or a linked state module.

• CalFile — the FTB's free, income-eligible direct-filing tool
• IRS Free File partners that also support California state returns
• The state module of commercial tax software used for the federal return
• Form 540 for full-year residents, or Form 540NR for part-year residents and nonresidents
• Paper filing by mail, for taxpayers who choose not to e-file

Deadlines, extensions, and penalties

California's filing deadline matches the federal deadline — April 15 in most years, moved to the next business day if that date falls on a weekend or holiday. California grants an automatic six-month filing extension without a separate request, but that extension applies only to filing the paperwork — tax owed is still due by the original April deadline, with penalties and interest accruing on unpaid balances after that date.

In years when the FTB or IRS declares a disaster-area postponement — for regions affected by wildfires, flooding, or similar events — both the filing and payment deadlines for affected counties can be pushed back, sometimes by several months. These postponements are announced separately from the standard extension and are specific to the declared disaster area.

California-specific tax credits

Some credits exist only at the state level. The California Earned Income Tax Credit (CalEITC) is available to lower-income working households and can be claimed alongside the federal EITC, using state-specific income limits that differ from the federal EITC thresholds. Households that qualify for CalEITC with a child under 6 may also qualify for the Young Child Tax Credit. A nonrefundable renter's credit applies to full-year residents who rented their home for at least half the year and meet the state's income limits, and a smaller Child and Dependent Care Expenses Credit is available as a state-level companion to the federal credit of the same name.

Frequently Asked Questions