We investigate the extent to which capitalization of expected capital gains taxes and the lock-in effect induced by the capital gains tax rate differential simultaneously impact the pricing and underpricing of initial public offerings (IPOs). Using a large sample of IPOs from 1987 to 2010, we estimate regressions of offer prices and first-day underpricing on tax rates. Supporting tax capitalization, IPO offer prices decrease in long-term capital gains taxes. Supporting lock-in, IPO underpricing increases in the long-term and short-term tax rate differential. These effects are consistent with capital gains taxes simultaneously reducing IPO proceeds and exacerbating IPO underpricing.