The Board of Governors discontinued the H.3 statistical release on September 17, 2020. For more information, please see the announcement posted on August 20, 2020.
Reserve balance requirements series is the portion of the reserve requirements not satisfied by vault cash. The series is calulated as Required reserves (REQRESNS) less Vault cash used to satisfy required reserves (VAULT).
Board of Governors of the Federal Reserve System (US), Reserve Balances Required; Reserve Balance Requirements (DISCONTINUED) [RESBALREQ], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/RESBALREQ, February 24, 2021.