How to File Late Tax Returns in California
Calculate the amount of income tax that you owe using your financial information. You may use one of the standard CA (540) forms or the worksheet provided on Form FTB 3519 to estimate your tax liability.
Pay the estimated amount of your tax liability by April 15 to avoid being charged a late payment penalty and interest. The penalty will be waived if you pay at least 90 percent of the tax by the due date. Form FTB 3519 offers four options for paying the tax: online payment, credit card, check or money order and through an installment agreement.
Mail your completed FTB 3519 to the address on the form only if you are paying by check or money order.
File your tax return by Oct. 15. The state gives you an automatic six-month extension, even if taxes were due. If you file after this date, you will be charged a late filing fee. If you do not owe taxes, no penalty is charged for filing late.