QSBS (Qualified Small Business Stock) is an IRS provision under Section 1202 that excludes up to $10M-$15M (or 10x basis) in capital gains from federal tax. The One Big Beautiful Bill Act (signed July 4, 2025) created a two-regime structure: stock issued on or before July 4, 2025 follows the pre-OBBBA rules ($10M or 10x cost basis cap, $50M gross-assets ceiling, 5-year hold for the full exclusion); stock issued after July 4, 2025 follows the OBBBA rules ($15M cap inflation-adjusted after 2026, $75M gross-assets ceiling, tiered holding with 50% exclusion at 3 years, 75% at 4 years, 100% at 5 years, maximum exclusion up to $750 million). The exclusion is available to founders, early employees, and early investors. It is one of the most v...