A portion, expressed in złoty, of the złoty and foreign currency funds held in bank accounts and of other funds. The minimum reserve requirement ratio for banks and its interest rate are set by the Monetary Policy Council.

The other funds include funds obtained from the sale of securities, with the exception of mortgage secured securities with the redemption period of over 5 years and mortgage bonds with the redemption period of over 5 years; and of other repayable funds taken by banks, with the exception of funds taken from another domestic bank, as well as funds taken from a foreign bank pursuant to agreements concluded prior to the entry into force of the present Act, or funds obtained from abroad for a period of at least two years, funds obtained pursuant to the contracts for maintaining individual retirement accounts and the contracts for maintaining individual retirement savings accounts within the meaning of the provisions on individual retirement accounts and on individual retirement savings accounts.