You down with OCC? The Office of the Comptroller of the Currency (OCC) regulates and supervises all nationally chartered commercial banks in the US (more than 1,650 of them), as well as some 50 federal branches of foreign banks. It performs on-site examinations of banks, reviews applications for new bank charters and branches, and issues and enforces rules governing bank practices. Established in 1863, the OCC is part of the US Department of the Treasury. It receives no Congressional appropriations, but rather receives most of its funding from national banks, which pay for their examinations.