Authorizes an income tax deduction for certain research expenses

SB 1231 modifies Missouri's income tax code by adding specific federal tax adjustments to Missouri taxable income. It requires taxpayers to add back certain items excluded from federal taxable income, such as federal tax refunds related to pandemic relief, interest on some government bonds, and specific business deductions (including research-related deductions under federal Section 174 for tax years 2022+). This affects Missouri residents and nonresidents filing state tax returns who claim these federal deductions. The bill does not create new tax deductions but adjusts how existing federal tax items impact Missouri taxable income. It aligns Missouri’s tax base more closely with federal calculations for certain items, effective for tax years beginning in 2022 or later.