Modifies provisions relating to motor fuel tax exemption

HB 3539 creates a refund program for Missouri residents who paid motor fuel tax on vehicles, directly affecting individuals and businesses that purchased fuel for vehicles registered in Missouri. It establishes two claim methods: a receipt-based refund requiring detailed vehicle and purchase documentation (filed by September 30 annually), or a standard refund applied as a flat amount against income tax (filed by April 15 annually). The standard refund amount increases yearly - $30 for 2026, $45 for 2027, $60 for 2028, and $75+ for 2029 onward - with receipts needed for the detailed option. Refunds are funded by the same motor fuel tax revenue and cannot exceed taxes collected in a given year.