The Mark-to-Market program preserves affordability and availability of affordable rental multifamily properties with federally insured mortgages, reducing rents to market levels by restructuring existing debt to levels supportable by these rents. This final rule revises the Mark-to-Market program regulations to clarify that annual adjustment of restructured rents under the program will be based on an operating cost adjustment factor determined by HUD and to further clarify when HUD may approve rent adjustments on a budget basis. This final rule will bring greater clarity to the Mark-to-Market program and will align HUD's regulations with recent legislative changes that specifically allow budget-based rent adjustments for the program.