Qualified Small Business Stock is a tax incentive to drive the investment and founding of small businesses in the United States of America. The QSBS regulations are under U.S. Code Section 1202 of the Internal Revenue Code. QSBS is a tax exemption on a federal, and in some cases, a state level. The tax benefit can exclude up to 100% of capital gains on the sale of QSBS held for five years. From Wikipedia