Quick pointer: this entry focuses on the tax-advantaged characteristics of founder-issued common stock (QSBS, 83(b), capital-gains holding-period math). For the structural setup at formation (RSPA, vesting, repurchase rights, the share split), see [Founders Stock].
Founder shares are the formation-stage common stock whose tax-advantaged characteristics convert a tiny dollar investment into a potentially massive tax-advantaged outcome. Those characteristics are Qualified Small Business Stock (QSBS) eligibility under §1202 (up to $10M-$15M or 10x basis excluded from federal capital gains per founder, with post-OBBBA stock issued after July 4, 2025 getting the $15M cap, a $75M gross-assets ceiling, and tiered holding periods),...