Relating to the withdrawal of a unit of election from certain metropolitan rapid transit authorities and the net financial obligation of that withdrawal.

HB 3643 modifies Texas law governing how municipalities or counties (called "units of election") can withdraw from metropolitan rapid transit authorities. It shortens the waiting period before a withdrawal election from five to two years after a previous withdrawal and establishes a new method for calculating a unit's financial obligation upon withdrawal. For small units (under 2% of the authority's total population), the bill replaces the standard calculation with the fair market value of remaining transit property. Transit authorities must annually estimate each unit's financial obligation and report it by July 1. This bill directly affects local governments seeking to leave regional transit systems.