Revenue and taxation; income tax; pensions; taxable income; exemption; effective date.

HB 1599 amends Oklahoma's tax code to adjust how businesses calculate state taxable income when carrying forward federal net operating losses (NOLs). It specifically changes the rules for carrying losses back to previous tax years: for 2007-2008, losses can only be carried back two years, and for later years, it aligns state loss carryback rules with federal Internal Revenue Code Section 172. This directly affects Oklahoma businesses that have federal NOLs, as it alters how they apply those losses for state tax purposes. The bill does not create new tax exemptions or change pension tax treatment, focusing solely on NOL calculation mechanics.