The bill amends the Middle Class Tax Relief and Job Creation Act, impacting the modification of existing wireless facilities. It states that state or local government may not deny an eligible facilities request for alterations if it doesn't substantially change the facility's physical dimensions. If the government does not approve the request within 60 days, it is automatically deemed approved. Additionally, if the initial request is incomplete, the 60-day timeframe is tolled until a supplemental submission is made. The Federal Communications Commission is required to issue final rules for implementation within 180 days of the Act's enactment, and the amendments apply to requests made after the Act's enactment.