Firms should use all available information to anticipate future tax rates. Firm mobility is one source of such information. We first show theoretically that governments increase tax rates on profits if average firm mobility decreases, and that the potential entry of immobile firms in the future deters firms from entering today. Building on prior evidence that German municipalities increase tax rates after the entry of immobile firms (wind power plants), we confirm that firms use this information to anticipate future tax rates. In the jurisdictions with the largest expected future tax rate increases, 10% fewer firms enter.