California calendar and forms

California’s calendar matches the federal one on the days that matter and departs from it on the amounts. Form 540 is due April 15, 2027, the same day as the federal return; the four estimated payment dates are the federal dates; and the extension is automatic to October 15, 2027, with no form to file. The difference is in the estimated payments: California wants 30% in April, 40% in June, nothing in September and 30% in January, so a filer who sends four equal federal-style quarters is short in June and penalized for it. The other difference is the Franchise Tax Board’s electronic-payment rule. Once a single payment tops $20,000 or a return shows more than $80,000 of tax, every later payment must be electronic, and a paper check after that costs 1%.

On the form side California is busier than most states, because Form 540 starts from federal AGI and then rebuilds much of the return its own way. Nearly every filer touches Form 540 and Schedule CA (540); parents with earned income add Form FTB 3514; anyone without health coverage for a month adds FTB 3853; heads of household add FTB 3532. The rest of the list below is for people who moved, who have income taxed by another state, who owe estimated tax, or who need to fix a return already filed.

The 2027 filing season, dated

How the extension really works

The Department grants every individual an automatic six-month extension to file. No request, no form, nothing to check on the return. What it does not do is extend the time to pay: in the Department’s words, “an extension to file your tax return is not an extension to pay.” Anyone who expects to owe should send the expected balance by April 15, with Form FTB 3519, Payment for Automatic Extension for Individuals, or through Web Pay, which does the same thing without the voucher. If nothing is due, send nothing and file by October 15. The late-payment penalty is 5% of the unpaid tax plus 0.5% for each month or part of a month it stays unpaid, up to 40 months; the Department waives it for reasonable cause, which it presumes if at least 90% of the tax was paid by April 15. Interest, 7% for the first half of 2027, is never waived. Someone outside the United States on April 15 has until June 15 to pay and December 15 to file, under the 2025 form’s rules.

Estimated payments: 30, 40, 0, 30

Estimated payments are required when the 2026 tax after withholding and credits is expected to be $500 or more ($250 married filing separately), and withholding plus credits is less than the smaller of 90% of the 2026 tax or 100% of the 2025 tax. Above $150,000 of 2025 California AGI ($75,000 separate), the prior-year safe harbor is 110%, and at $1,000,000 of 2026 AGI ($500,000 separate) there is no prior-year safe harbor at all. The required annual payment is split 30% by April 15, 40% by June 15, nothing by September 15 and 30% by January 15, a schedule the legislature adopted during the 2009 budget crisis to pull cash into the state’s fiscal year. The underpayment penalty is figured on Form FTB 5805 as the Department’s interest rate on each short installment for the days it was short. The people most often caught are the self-employed, anyone with a large capital gain or Roth conversion, and retirees whose IRA withdrawals had federal withholding but no California withholding, which happens because the payer must be told separately, on Form DE 4P.

The forms, in the order a filer meets them

Filing free, paying and checking a refund

CalFile is the Department’s own free e-file for the state return. It requires a MyFTB account, which requires having filed a California return in one of the last five years; most people can register in minutes, some are mailed a PIN. It files only the California return; the federal return goes separately through IRS Free File or software. The Department also lists commercial Free File partners by income, and VITA sites prepare both returns for lower-income households. IRS Direct File, which handed California filers to CalFile in the 2025 filing season, was discontinued before the 2026 season and has not returned.

Payments go through Web Pay at ftb.ca.gov/pay, free by bank debit, or by card through a processor that charges a fee. Checks for a return with a balance due go to Franchise Tax Board, PO Box 942867, Sacramento CA 94267-0001; returns with a refund or nothing due go to PO Box 942840, Sacramento CA 94240-0001. Remember the electronic-payment rule before writing a check.

Where’s My Refund at ftb.ca.gov/refund needs the Social Security number, ZIP code, exact refund amount and the street-number part of the mailing address. Allow up to three weeks for an e-filed return and up to three months on paper; returns picked for identity review take longer, and the Department mails a letter when the refund amount changes. Live help is at 800-852-5711, weekdays 8 AM to 5 PM; the automated line at 800-338-0505 runs around the clock for refund status, balances and forms. Online chat is available from the contact page, and MyFTB shows payments made, balances and letters.