Interest Rates

The interest rate applied to unpaid or underpaid taxes is based on the rate charged by the Internal Revenue Service plus 3 percent. Every January and July, the California Department of Tax and Fee Administration (CDTFA) evaluates the rates. If CDTFA determines that a rate change is required, the change takes effect 6 months later and remains in effect for at least 6 months.

An interest calculator is available to help you calculate the interest due.

For more information about when interest applies and when you may be relieved of interest charges, see publication 75, Interest, Penalties, and Collection Cost Recovery Fee.

Interest Rates for Unpaid or Underpaid Taxes
(these rates do not apply to IFTA)

Beginning – Ending
"Debit" Rate for Deficiencies "Credit" Rate for Refunds Monthly Factor


  1. These rates do not apply to the IFTA (International Fuel Tax Agreement) program. For more information on IFTA rates, you can visit the International Fuel Tax Agreement (IFTA) – Interest Rates page.
  2. Applied to each month or fraction of a month that a tax or fee payment is overdue or a refund is owed.

Note: Interest on Timber Yield Tax accounts was calculated daily up until December 31, 2021. Beginning January 1, 2022, interest on Timber Yield Tax accounts will be calculated monthly as shown above. See the Timber Yield Tax Interest Rates page for rates prior to January 1, 2022.