What Should I Do If I Missed a California Tax Deadline or Received an FTB Notice?

A missed California income-tax deadline usually shows up as a Franchise Tax Board (FTB) letter weeks or months later. The letter tells you more than the amount: it identifies the tax year, why FTB acted, and how and when it wants a response. Before deciding whether to pay, file, or dispute, read the notice against FTB's published rules. A late return, a late payment, and a missed estimated payment each carry a different penalty and a different path to relief.

Read the FTB notice before choosing a response

FTB sends notices when there is a balance due, when it changed a return, when it needs more information, or when a return was not filed. Its notices and letters page lists common examples by form number, such as a Demand for Tax Return (FTB 4601) or a Notice of Tax Return Change (FTB 5818). FTB's instructions are direct: read the notice carefully; if you agree, follow its instructions; respond by mail, fax, or online as the notice specifies; pay as much as you can, even if not the full amount; and keep a copy with your tax records.

Not every notice accepts every response method. FTB says some cannot be answered by electronic upload, so the notice controls. Some notices also carry their own short response period; FTB lists 30 days from the notice date for certain documentation requests, for example.

Identify the tax year, amount, and stated deadline

Write down the tax year, the notice number and date, the amount, and the response date. Then compare them with the deadline that was missed. For 2025 returns, FTB's personal due dates were April 15, 2026 to file and pay. FTB grants an automatic extension to file until October 15, 2026, but its extension page states that "an extension to file your tax return is not an extension to pay." Someone who filed by October 15 but paid after April 15 may still owe a late-payment penalty and interest.

FTB's penalty page shows why the distinction matters:

• Late filing (RTC 19131): 5% of the amount due per month or part of a month, up to 25%. If an individual return remains unfiled more than 60 days after the filing deadline (including any extension), RTC 19131(b) sets a minimum of $135 or 100 percent of the amount of tax required to be shown on the return, reduced by timely payments and credits, whichever is less, unless the failure is due to reasonable cause and not willful neglect. FTB explains the resulting amounts for balances of $540 or less.
• Late payment (RTC 19132): 5% of the unpaid tax, plus 0.5% per month for up to 40 months.
• Demand penalty (RTC 19133): 25% when a return is not filed by the date on a Demand for Tax Return, even if the return shows a refund.
• Estimated tax penalty (RTC 19136): computed like interest on each late or short installment.

Gather filing, payment, and delivery records

Collect the return as filed, with the e-file acknowledgment or proof of mailing; every payment confirmation, including any extension payment (FTB 3519) and estimated payments (Form 540-ES); and the notice with its envelope. A MyFTB account shows account history and lets you respond to some notices online. If your records show a payment or filing that the notice does not reflect, note the date and amount, because that discrepancy is usually the first thing to raise.

If a hardship caused the delay, such as illness, a disaster, or an error by a preparer or a bank, keep documents showing when it began and ended. They matter if you later ask FTB to remove a penalty.

Requesting review or relief through the correct process

If you disagree with the notice, FTB's dispute page directs you to respond through the channel the letter identifies. You can also pay the full amount, which stops further penalties and interest, and then file a claim for refund. If an ongoing problem is not being resolved, FTB's Taxpayer Advocate is available.

For individuals, California now offers a one-time penalty abatement under RTC 19132.5. FTB's abatement page says it is a once-in-a-lifetime waiver of late-filing and late-payment penalties for tax years beginning on or after January 1, 2022. It is available to individuals under the Personal Income Tax Law, not estates or trusts. To qualify, you must be current on filing, must not have received this abatement before, and must have paid in full or be current on an installment agreement. You can request it through MyFTB, on Form FTB 2918, or by phone at 800-689-4776. FTB identifies it as an alternative to reasonable-cause relief. Because it is available only once, a taxpayer may want to discuss which relief to request for the particular year.