In the United States, small banks (those with less than $15.2 million in
transaction accounts) have no
minimum reserve
requirement. Banks with $15.2 million to $110.2 million in
transaction accounts must hold 3% in reserve. Large banks (those with more than $110.2 million in
transaction accounts) must hold 10% in reserve.
These reserves must be maintained in case depositors want to withdraw cash from their accounts. Banks may keep reserves in two ways. They can keep cash in their vault, or they can deposit their reserves into an account at their local Federal Reserve Bank.