OK HB2730

Replaces fixed 1.25% monthly interest rate on delinquent state taxes with annual rate calculated using Wall Street Prime as of January 1 plus 3 percentage points.

Applies the same Wall Street Prime-based formula to deficiency assessments under Section 221 and estimated tax payment underpayments, replacing the prior fixed 20% annual rate for underpayments.

New interest rates apply to all delinquencies occurring on or after November 1, 2025, and retroactively to any delinquent accounts already in existence as of that date.

Maintains existing penalty provisions for late payments (10% for sales/use/motor fuel taxes after 15 days, 10% for other taxes after 30 days) and deficiency-related penalties (25% for negligence, 50% for fraud).

Effective date: November 1, 2025.