If an existing sign is located within the incorporated boundaries of a municipality that is approved by the department to control commercial signs under §21.192 of this subchapter (relating to Local Control of Commercial Signs) and the sign will be relocated within the incorporated boundaries of the same municipality, permission to erect the sign must be obtained only from the municipality in accordance with the municipality's sign and zoning ordinances, and the department will not issue a credit to erect a sign unless the sign owner provides a certified document from the city stating that the city is declining to allow the relocation.