409A valuation refers to the process of determining the fair market value of a company's common stock for setting the exercise price of employee stock options, as required by Section 409A of the Internal Revenue Code. Failing to comply with 409A valuation regulations can result in significant financial penalties for both companies and employees. 409A valuation ensures stock options are granted at a fair price and allows employees to benefit from potential growth in the company's value over time. It is a complex process that often involves valuation experts and considers various company financials and market approaches. For startups and private companies, meeting 409A valuation requirements is critical to avoid penalties, and non-compliance can lead to immediate taxation of stock options at the time of grant.