Disclaimer

OptionBasis is a calculator, not advice. Nothing on this site is investment, tax, legal or accounting advice, and nothing here is a recommendation to buy, sell or hold any security or to use any options strategy.

The numbers are a trading view, not a tax view. Share cost basis is computed with the average-cost method and option premium is netted against it. Your broker and the IRS use lot-based methods and treat option premium differently (for example, an assigned put's premium adjusts the stock's basis, while an expired call's premium is a short-term gain). Use your broker's tax documents for tax reporting.

Accuracy. Results depend entirely on the statements you load. Missing months, unsupported brokers, corporate actions, and unusual fills can all produce wrong numbers. The tool flags the cases it can detect; verify anything you rely on.

Referrals and ads. Some links are broker referral links; we may be compensated if you open an account through them. That does not influence the calculations.

Options involve risk and are not suitable for all investors.