How to fill out CA Form 540 (income tax), line by line

• Start with the right California return and filing status

• Calculate California income and tax: lines 12-35

• Credits, other taxes, and payments: lines 40-78

• Use tax, health coverage, refund, or amount due: lines 91-117

• Finish, attach, and sign Form 540

Start with the right California return and filing status

Resolve residency and filing status before entering income. Those choices affect later deductions, exemption credits, and the tax calculation.

Before entering a line: resident return, federal return, and filing date

Use Form 540 if you and, on a joint return, your spouse or RDP were California residents for all of 2025. If either person was not a resident for the entire year, the FTB directs you to Form 540NR instead. Form 540 is not a substitute for the nonresident or part-year resident return. If this is not the form you need, browse the broader government form instructions hub.

For most filers, April 15, 2026 is the date to file and pay the 2025 amount owed without penalties and interest. October 15, 2026 is the extended filing date for avoiding a late-filing penalty, but interest is calculated from the original due date. If you cannot file by April 15 and expect to owe tax, follow the FTB 3519 extension-payment instructions rather than treating the extension as extra time to pay.

On Side 1, use black or blue ink, capital letters, and aligned dollar amounts. Leave a line blank when you have no entry unless its instructions specifically say to enter -0-. The principal-residence county and physical-address area is conditional: leave it blank if you are under 18 or did not file a California resident return in the prior year. Otherwise, check the same-address box when appropriate or enter the physical residence address at filing.

Lines 1-11: filing status, dependent status, and exemption counts

Check only one filing-status box on lines 1-5. California status usually matches federal status, but registered domestic partners who filed federally as single must use married/RDP filing jointly or separately for California. A joint federal filer can use separate California returns only in specified military or full-year-nonresident circumstances; community-property rules can prevent the nonresident-spouse exception. Head-of-household filers must attach FTB 3532.

1. Check line 6 when someone can claim you or your spouse/RDP as a dependent, even if that person does not actually claim you.

2. Enter only the permitted counts on lines 7-10. Each personal, blind, and senior count is multiplied by $153; each dependent count is multiplied by $475.

3. Add lines 7-10 on line 11. That amount normally transfers to line 32, where it reduces tax.

• government form instructions

Calculate California income and tax: lines 12-35

These lines create the central bridge from your completed federal return to California taxable income and tax. Use the source the form names; California adjustments are not amounts to estimate independently.

Lines 12-19: from federal AGI to California taxable income

Major income and deduction entries

Subtract line 14 from line 13 for line 15, then add line 16 for California adjusted gross income on line 17. If line 13 is less than zero, the instructions instead tell you to combine lines 13 and 14 and show the result in parentheses. For line 18, compare California itemized deductions with the California standard deduction. The printed standard deduction is $5,706 for single or married/RDP filing separately and $11,412 for married/RDP filing jointly, head of household, or qualifying surviving spouse/RDP. Separate spouses/RDPs must both itemize or both use the standard deduction; a person claimable as a dependent uses the California Standard Deduction Worksheet for Dependents.

Lines 31-35: choose the tax method and apply exemption credits

Use the 2025 Tax Table when line 19 is $100,000 or less. Use the Tax Rate Schedules when it is over $100,000, unless a specialist computation such as FTB 3800 or FTB 3803 applies to your situation. Enter the calculated tax on line 31. Line 32 ordinarily receives line 11, then line 33 subtracts exemption credits from line 31 and cannot be below zero. Line 35 adds line 33 and any line-34 special tax.

Credits, other taxes, and payments: lines 40-78

This part of Form 540 keeps two different ideas separate: credits and other taxes determine total tax, while withholding, payments, and refundable credits determine total payments. Keep each amount in its designated lane.

Lines 40-64: credits and other taxes change total tax

Lines 40-48 cover nonrefundable credits, including child and dependent care expenses and renter's credit, plus any special credits entered with their names and codes. Most special credits require a separate form or schedule to establish the amount. Use Schedule P (540) when the instructions require it, including when claiming more than two credits. Line 48 is tax after credits; lines 61-63 add specified other taxes and credit recapture. Line 64 is total tax—the figure later compared with payments.

Lines 71-78: keep withholding, payments, and refundable credits separate

Where payment-related amounts belong

Do not include city, local, county, other-state, or nonconsenting nonresident member tax on line 71. Lines 75, 76, and 77 receive the California EITC, Young Child Tax Credit, and Foster Youth Tax Credit from FTB 3514 lines 20, 28, and 39 when applicable. Add lines 71-77 for line 78. That total is not the final refund: the form next applies the required use-tax and health-coverage-penalty calculations.

Use tax, health coverage, refund, or amount due: lines 91⁠–⁠117

The final calculation follows the form's order. It first compares total payments with use tax, then compares any remaining payment balance with an Individual Shared Responsibility penalty, before comparing the resulting payment amount with total tax.

Lines 91-96: use tax and the health-coverage penalty route

Line 91 cannot be blank. Enter use tax, or enter zero and check whether no use tax is owed or the obligation was paid directly to CDTFA. Use tax can apply to taxable merchandise bought from an out-of-state seller for use in California when California sales or use tax was not paid. Use the Use Tax Worksheet when you want to calculate actual purchases, have a covered business purchase, or bought any individual item costing $1,000 or more. Some business purchasers must report directly to CDTFA instead, including those with or required to have a seller's permit, those exceeding the stated $10,000 purchase condition, or those otherwise required to register with CDTFA.

For line 92, check the coverage box only when you, a spouse/RDP on a joint return, and anyone you can or do claim as a dependent had qualifying health care coverage for all of 2025. Medicare Part A or C qualifies. If you cannot check the box, use Form FTB 3853 to determine whether an Individual Shared Responsibility penalty applies and, if so, the amount to enter. Lines 93-96 then perform the form's separate payment comparisons for use tax and the ISR penalty.

Lines 97-117: choose a refund or payment path and complete it

If line 95 exceeds line 64, line 97 is overpaid tax; if it is lower, line 100 is tax due. An amount elected on line 98 applies to 2026 estimated tax and is binding, so line 99 is what remains available this year. Voluntary contributions on codes 400-449 total on line 110 and either reduce the overpayment or increase what is due. Where line 111 has an amount, line 114 adds lines 111-113. For a refund or no amount due, line 115 follows the line-99 path after required contributions, interest, and penalty entries.

Finish, attach, and sign Form 540

A correct calculation still needs a complete filing package. Treat Side 6 and the attachment order as part of completing the return, not as afterthoughts.

Attachments, mailing path, and signatures

1. Put all six sides of Form 540 in numerical order. Side 6 must be signed; both spouses/RDPs sign a joint return.

2. Attach W-2, W-2G, 1099, 592-B, and 593 withholding documents to the lower front of the return. Then place required California schedules/forms behind Side 6, followed by required federal documents.

3. Use the amount-due mailing route when payment is enclosed; use the refund/no-amount-due route for the other result. Do not send cash, and do not staple a check or money order to the return.

The voter-information checkbox is optional. The health-care-information choice authorizes limited sharing of return information with Covered California if you select Yes. The organ-donor election is also optional, but checking it and signing the return gives written consent for Donate Life California registration and the stated information sharing. A third-party designee may handle limited return-processing communications, but cannot receive your refund, bind you, or represent you before the FTB.

I did not receive a W⁠–⁠2. What should I do?

Contact your employer first; only the employer can issue or correct a federal Form W-2. If you cannot obtain a copy, complete FTB 3525 as instructed. Do not send missing withholding documents separately after filing unless the FTB asks for them.

What if I cannot pay the full amount due?

Pay as much as possible when you file. You may request monthly payments with FTB 3567, but do not mail that request with the return. Interest and an underpayment penalty may still apply to tax unpaid by April 15, 2026, even if the request is approved.

How do I correct a filed Form 540?

If an error affects California tax liability after you file, submit an amended Form 540, check the AMENDED box, and attach Schedule X with the needed supporting forms. Do not amend merely to correct a use-tax error reported on the original return; the instructions direct those questions to CDTFA.

Sources and how this page was made

This guide explains the official sources listed below in plain language. Displayed amounts, limits, percentages, and timing rules come from that material.

Source revision reflected in this guide: Instructions: 2025.

• Official form: 2025 Form 540 California Resident Income Tax Return

• Official form instructions: 2025 Personal Income Tax Booklet | California Forms & Instructions 540 | FTB.ca.gov — IRS