The recently-signed Protecting Americans from Tax Hikes Act of 2015 reinstates some expired tax benefits retroactively and makes them permanent. On the list is the 100% tax exclusion of the gain from sales of qualified small business stock (QSBS).
Example 1: Nick Oliver creates a company in 2016 and sells all the stock in it in 2022 for a $3 million gain. If the stock meets the requirements to be QSBS, Nick will owe no tax on that $3 million profit. (In most cases, tax-free gains of QSBS are capped at $10 million.)