Under IRC Section 1202(a)(1), that cooking time is five years. However, once you've held the QSBS for five years, IRC Section 1202(b) allows you to exclude up to the greater of (1) $10 million of gain or (2) 10
This paper provides a brief overview of the requirements for QSBS status, the difficulty of interpreting the restrictions on the amount of gain exclusion under I.R.C. [section] 1202, the impact of the alternative minimum tax, and the adjustments necessitated by the appreciated property rule. ...