Qualified Small Business Stock, or QSBS, is a tax benefit that can have substantial advantages to startup investors. Investors in companies that qualify can save up to $10M a year, or 10x their investment, in capital gains.Basic QSBS requirements are: The company needs to be a Delaware C-corp company. It must have less than $50 million in net assets on a tax basis. The business must be in a hard science or innovation space. The stockholder must own the stock for at least 5 years.There are some other nuances, so you need to consult with a qualified tax CPA for both the company and for the individual taxpayer.