If you cannot exchange the money personally you may send them to the National Bank of Slovakia by post. Instructions  are at the web page: https://nbs.sk/en/banknotes-and-coins/exchange-of-money/exchange-of-slovak-banknotes-and-slovak-coins The address for sending money by the registered letter: National Bank of Slovakia Cash Handling Section Imricha Karvasa 1 813 25 Bratislava Slovakia You will be informed about the exchange of money by a letter from the Cash Handling Section.