Under Section 1202, the maximum gain exclusion is the greater of $10 million or ten times the adjusted basis of the Qualified Small Business Stock (QSBS) sold. If your adjusted basis in the stock is below $1 million, you can exclude up to $10 million from your taxable income. Meanwhile, if your adjusted basis exceeds $1 million, you can exclude up to ten times that amount. In theory, a taxpayer could achieve a maximum gain exclusion of just under $500 million if they have an adjusted basis of right under $50 million and subsequently sold their stock for more than $500 million or more.