An 83(b) Election is a tax filing made by the holder of stock subject to vesting to be immediately taxed on the difference in value between the fair market value of the stock and the price the holder paid for the stock. If an 83(b) election is not made, the holder would owe taxes on the difference between the fair market value of the stock and the price the holder paid for that stock as of the date that the stock vests. An 83(b) election must be made within 30 days of the purchase of the stock.