Cost basis is original price of an asset for tax purposes (usually the purchase price), adjusted for stock splits, dividends and return of capital distributions. This cost basis value is used to determine the capital gain. The cost basis Calculator can do in seconds what might otherwise take days. Simply by supplying the security, price paid, amount purchased, date of purchase and date of sale, the calculator can automatically calculate the adjusted cost basis taking into account all splits, spin-offs, and distributions. In an instant, it is determined for any security and over any holding period back to 1900. Results include the date of the corporate action, the type of action, and the allocation with a running total of current cost basis and current shares.