Mobile Telecommunications Sourcing Act

Authorizes a State or a designated database provider to provide an electronic database to a home service provider in a format which designates for each street address the appropriate taxing jurisdiction as identified by a nationwide standard numeric code. Requires the State or designated database provider to provide notice of the availability of such electronic database, as well as subsequent revisions thereto. Holds harmless from any fee liability a home service provider that uses such database. Holds a provider harmless from any such liability in the absence of such a database if the provider employs an enhanced zip code to assign each street address to a specific taxing jurisdiction and exercises due diligence to ensure that each address is assigned to the correct taxing jurisdiction. Requires one specific taxing jurisdiction to be assigned when an enhanced zip code overlaps boundaries of different taxing jurisdictions. Terminates the authority to use the enhanced zip code on the later of: (1) 18 months after the nationwide standard numeric code has been approved; or (2) six months after a such electronic database is provided.

Authorizes a taxing jurisdiction, or a State acting on behalf of such jurisdiction: (1) to determine the place of primary use for purposes of appropriate taxing authority; and (2) if necessary, to notify a home service provider to change the assignment of a taxing authority to reflect the appropriate place of primary use. Authorizes a taxing jurisdiction to require the home service provider to obtain and maintain the customer's place of primary use for taxing purposes. Provides transition provisions and special rules.