We publish methodological recommendations for banks on identifying sources of funds when their customers make transactions with large amounts of cash. Such measures are necessary for banks to immediately identify suspicious transactions that may be aimed at laundering the proceeds of crime, including the introduction of shadow cash into legal circulation. The measures focus on transactions with large amounts of cash (for citizens - from 5 million rubles once or in total per month), which are not typical for business of companies or payments to households of individuals. They concern a narrow segment of bank customers and do not affect the interests of conscientious citizens. The recommendations are consistent with the principles of the Financial Action Task Force (FATF), which emphasize sourcing issues in customer due diligence procedures. The recommendations help make these procedures more understandable for financial institutions and their customers. The document includes recommendations previously issued by the Bank of Russia aimed at preventing the circulation of cash from an unknown source, therefore previous recommendations on this issue are cancelled.