Authorizes an income tax deduction for capital gains

HB 508 modifies Missouri's income tax code to align the state's calculation of taxable income with federal treatment of capital gains. It repeals an existing section and replaces it with a new provision requiring Missouri taxpayers to add back federal capital gains deductions to their federal adjusted gross income when calculating state tax liability. This directly affects Missouri residents who claim capital gains deductions on their federal tax returns, as it ensures those deductions are properly accounted for in their Missouri tax calculation. The bill does not create new deductions but adjusts how existing federal capital gains deductions are treated under Missouri law.