California Form 100: Filing, Deadlines, and Payment

California Form 100 is the annual franchise or income tax return that C corporations file with the Franchise Tax Board to report net income and calculate what they owe. Calendar-year filers must submit it by April 15, and the state grants an automatic seven-month extension to November 15 — but any tax owed is still due by the original April deadline.1Franchise Tax Board. Due Dates: Businesses The standard rate is 8.84 percent of net income, with an $800 minimum franchise tax for most active or registered corporations.2Franchise Tax Board. C Corporations

Who Has to File

Every corporation incorporated in California, qualified to do business here, or actively conducting business in the state must file Form 100.3Franchise Tax Board. 2025 Corporation Tax Booklet A corporation is “doing business” in California if it meets any of three activity thresholds: California sales exceeding the lesser of $500,000 or 25 percent of total sales; real or tangible personal property in the state exceeding the lesser of $50,000 or 25 percent of total property; or California-based compensation exceeding the lesser of $50,000 or 25 percent of total compensation paid.4California Legislative Information. California Revenue and Taxation Code RTC 23101 The FTB adjusts those dollar amounts annually, so confirm the current figures in the tax year’s booklet.

A corporation that had zero revenue or operated at a loss still owes the $800 minimum for every year it remains active or registered with the Secretary of State.2Franchise Tax Board. C Corporations One exception: corporations incorporated or qualified on or after January 1, 2020, are exempt from the minimum franchise tax in their first taxable year.5Franchise Tax Board. Corporations

What to Gather Before You Start

  • Your Federal Employer Identification Number (FEIN).6Franchise Tax Board. 2025 Instructions for Form 100-ES Corporation Estimated Tax
  • Your seven-digit California Corporation Number from the Secretary of State.
  • Your completed federal Form 1120 — Form 100 starts from federal taxable income before net operating loss and special deductions.
  • The exact beginning and ending dates of the tax year. Fiscal-year filers need the form version that matches that year.
  • Supporting schedules you’ll need for your situation (listed below).

Download the form and its booklet from ftb.ca.gov, and match the version to the tax year you’re reporting. The booklet contains line-by-line instructions, any rate changes, and the current federal conformity rules.

Working Through the Return

Start With Federal Taxable Income

Line 1 of the state adjustments section asks for net income before state adjustments, which is federal taxable income from Form 1120. California uses that figure as the starting point but doesn’t conform to every provision of the Internal Revenue Code, so the following lines add back or subtract amounts where state law differs.3Franchise Tax Board. 2025 Corporation Tax Booklet

Common adjustments on Side 2 include adding back state, local, and foreign income taxes deducted federally, and correcting depreciation and amortization where California’s rules diverge. Depreciation differences are computed on Form FTB 3885 and attached to the return.7Franchise Tax Board. California Corporation Franchise or Income Tax Return Form 100 The booklet walks through each adjustment line.

Apportion Income if You Operate in More Than One State

If your corporation earns income both inside and outside California, you don’t pay California tax on all of it. Schedule R calculates the share apportioned to the state.8Franchise Tax Board. 2025 Instructions for Schedule R Most corporations use a single-sales-factor formula: California sales divided by total sales everywhere. Agriculture, extractive, and certain other industries still use the older three-factor formula weighing property, payroll, and sales. Attach Schedule R behind the return and before your other supporting schedules.

Calculate the Tax

Apply 8.84 percent to your California net income after adjustments and apportionment.9California Legislative Information. California Revenue and Taxation Code RTC 23151 Banks and financial corporations use 10.84 percent.10Franchise Tax Board. Business Tax Rates If the calculated tax comes to less than $800, enter $800 — the minimum applies to every active or registered corporation except those in their first taxable year.

Claim Credits

California credits reduce tax owed dollar for dollar. Commonly claimed ones include the Research Credit, the California Competes Tax Credit, the Low-Income Housing Credit, and the California Motion Picture and Television Production Credits.3Franchise Tax Board. 2025 Corporation Tax Booklet Each has a code number listed in the booklet’s Credit Chart. If you’re claiming one or two credits, enter them directly on Lines 24 and 25. For three or more, use Schedule P (100) and carry the total to Line 26.

Subtract What You’ve Already Paid

Enter the total of any estimated tax payments you made during the year on Form 100-ES, along with any overpayment applied from the prior year and any payment sent with an extension. The difference between total tax and total payments produces either a balance due or a refund.

Schedules and Attachments You May Need

Form 100 rarely stands alone. Which schedules apply depends on your activities. The most common are:11Franchise Tax Board. 2024 Corporation Tax Booklet 100

  • Schedule R — apportionment and allocation of income for multistate operations.
  • Schedule H (100) — dividend income deduction.
  • Schedule P (100) — alternative minimum tax and credit limitations, and required for claiming more than two credits.
  • Form FTB 3885 — corporation depreciation and amortization where California and federal amounts differ.
  • Form FTB 3805Q — net operating loss or disaster loss deduction computation.
  • Form FTB 5806 — underpayment of estimated tax, when using Exception B or C to reduce or eliminate the penalty.
  • Schedule D — capital gains and losses.
  • Schedule M-1 — reconciliation of income per books with income per return.

When It’s Due

Calendar-year corporations must file by April 15. Fiscal-year filers must file by the 15th day of the fourth month after their year ends.1Franchise Tax Board. Due Dates: Businesses

California grants an automatic seven-month extension. No separate form is required to request it, so a calendar-year return that would have been due April 15 becomes due November 15. The extension covers filing, not paying. Any tax owed is still due by the original date, and if you expect to owe, send a payment with a completed Form 100-ES voucher by then to avoid penalties and interest.

How to File and Pay

E-Filing Is Usually Required

California law requires any business entity that prepares its return using tax preparation software to file electronically.12Franchise Tax Board. e-file for Business For most corporations using a preparer or commercial software, e-filing is mandatory. The FTB may grant a waiver for technology constraints, undue financial burden, or other reasonable cause, but the default is electronic. E-filing produces immediate confirmation of receipt and faster processing.

Mailing a Paper Return

If you qualify for a waiver, the address depends on whether you’re enclosing a payment:13Franchise Tax Board. Mailing Addresses

  • Without payment: Franchise Tax Board, PO Box 942857, Sacramento, CA 94257-0500
  • With payment: Franchise Tax Board, PO Box 942857, Sacramento, CA 94257-0501

The ZIP codes differ by a single digit. The wrong box delays processing, so double-check before you seal the envelope.

Paying Online

The FTB’s Web Pay portal lets you pay directly from a business checking or savings account at no charge.14Franchise Tax Board. Pay by Bank Account (Web Pay) You can use it for annual tax, estimated installments, extension payments, and balances due on a filed return. Enter your FEIN and California Corporation Number to route the payment to the correct account and year. Submit separate payments for different tax years; bundling them causes processing delays.

Estimated Tax During the Year

Corporations expecting to owe more than $500 for the year should make estimated tax payments using Form 100-ES. The $800 minimum franchise tax is due with the first installment in the first quarter of the accounting period. Missing an installment triggers an underpayment penalty running from the installment due date until the earlier of the payment date or the return due date.15Franchise Tax Board. Common Penalties and Fees

What Late Filing or Late Payment Costs

The delinquent filing penalty is 5 percent of the unpaid tax for each month or partial month the return is late, up to 25 percent.15Franchise Tax Board. Common Penalties and Fees The percentage applies to what’s unpaid after crediting anything you paid by the original due date, so paying on time softens a late filing.

Interest compounds on unpaid tax from the original due date. For the period from July 1, 2025, through June 30, 2026, the corporation underpayment interest rate is 7 percent.16Franchise Tax Board. Interest and Estimate Penalty Rates The rate is adjusted twice a year, so a balance that spans multiple periods may carry different rates across the timeline. Even if you need the seven-month extension to finish the return, pay what you owe by the original due date.

Filing a Final Return When You Close

A corporation that shuts down or dissolves must file a final Form 100 covering its last year of operations. Check the “Final Return” box on the first page and write “FINAL” at the top.17Franchise Tax Board. Closing a California Business Entity Pay all outstanding balances, including penalties, fees, and interest on any delinquent returns, before filing. The corporation must cease doing business in California after the final taxable year.

Filing the final return with the FTB is only part of it. You also need to file dissolution paperwork with the Secretary of State, and foreign corporations need a certificate of surrender or withdrawal. Skip those steps and the corporation stays on the books, accruing the $800 annual minimum year after year. Keep your records after closing, because final returns remain subject to audit until the statute of limitations expires.