The FTB has released the interest rates for the second half of 2026. (FTB Tax News (February 2026)) For the period July 1, 2026, through December 31, 2026, the rates remain unchanged from the first half of 2026:
- Personal underpayment/overpayment and corporate underpayment: 7%; and
- Corporate overpayment: 4%.
You can access historical rates at:
www.ftb.ca.gov/pay/penalties-and-interest/interest-and-estimate-penalty-rates.html
