State Tax Day - Current, S.3, Kansas—Multiple Taxes: Interest Rates Set for 2026 Tax Year, (Dec 17, 2025)
The interest rates for the underpayment and overpayment of various Kansas taxes, including income, sales and use, and motor fuel taxes, is set at 8% for the period from January 1, 2026 to December 31, 2026.
Penalty and Interest Rates, Kansas Department of Revenue, December 2025