The FTB has released the interest rates for the first half of 2027. (FTB Tax News (September 2026)) For the period January 1, 2027, through June 30, 2027, 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
