This document contains final regulations that provide rules for claiming the railroad track maintenance credit under section 45G of the Internal Revenue Code for qualified railroad track maintenance expenditures paid or incurred by a Class II railroad or Class III railroad and other eligible taxpayers during the taxable year. These final regulations reflect changes to the law made by the American Jobs Creation Act of 2004, the Gulf Opportunity Zone Act of 2005, and the Tax Relief and Health Care Act of 2006.