Reserve Banks provide a number of banking and financial services to the U.S. Treasury, including two major services.

The Treasury's Checking Account
Incoming federal government revenues are credited to the U.S. Treasury's accounts at Reserve Banks. Most of these revenues come from transfers of funds from depository institutions in which the Treasury initially deposited its receipts from taxes and the sale of securities. The transfers are accomplished by debiting the depository institutions' reserve balances with the Federal Reserve and crediting the Treasury's account with the Fed. The Treasury spends these funds primarily by issuing checks or ACH entries, such as Social Security and armed services payroll checks or EFT payments. These checks or entries are submitted for collection to Reserve Banks, where they are charged against the Treasury's account.

The Treasury's Fiscal Agent
When its current expenses run ahead of its current cash resources, the Treasury borrows, mostly by auctioning government securities to investors. The auctions are held by the Federal Reserve Banks, acting as the Treasury's fiscal (financial) agents. The Fed also inscribes and delivers U.S. savings bonds sold through depository institutions and other issuing agents.