Revise income tax laws to provide conforming changes for prior legislation

This bill updates Montana's income tax laws to align with recent federal tax simplification measures, directly affecting state taxpayers and the Department of Revenue. It adjusts how Montana taxable income is calculated by adding certain federal deductions back to income and subtracting specific exemptions, including changes to how S-corporation income, qualified business income deductions, and state tax deductions are treated. The legislation also clarifies definitions for education savings account withdrawals, extends filing deadlines when they fall on federal holidays, and removes a requirement for the Department of Revenue to provide estate tax certificates to court clerks. These technical adjustments ensure Montana's tax code remains consistent with prior federal and state tax simplification legislation without changing overall tax rates or fundamental tax obligations.