The total amount of money and property you contribute to an S corporation in exchange for its stock equals your initial stock basis. At the end of each year you must increase or decrease your stock basis to account for your share of certain items (covered next).
You must adjust your stock basis at the end of each tax year. After making the adjustments, the final result is your adjusted stock basis. Stock basis is important. It is used to determine the amount of a loss you may deduct on your individual income tax return, the amount of a distribution you may take before incurring a taxable capital gain, and your gain or loss if you sell your stock.