Revenue and taxation; income tax; adjustments; retirement benefits; effective date.

HB 1391 amends Oklahoma's income tax code to adjust how taxable income is calculated for individuals and corporations. It specifically revises rules for federal net operating loss deductions (including carryback periods and allocation methods) and clarifies how income from property (real or intangible) and business activities should be allocated to Oklahoma for tax purposes. The bill directly affects businesses and taxpayers who claim federal deductions or operate across state lines, requiring them to adjust their Oklahoma tax calculations based on Oklahoma-specific rules. Key changes include aligning Oklahoma's loss carryback rules with federal timelines for certain tax years and defining how income from property or sales is allocated to Oklahoma. This is a technical adjustment to Oklahoma's tax code, not a new tax or benefit.