When a foreign customer pays for services, first the money is deposited in a special transit account with a bank. To get and use them you need to prove the transaction. Sometimes, only an invoice is enough for this, where there is information about you, the counterparty, the service, the timing, amount, and form of payment. In some cases, the bank may require a contract and an act of completed work, other additional documents. This package depends on the internal policy of the bank, regulations of the Central Bank, and tax legislation. In any case, all questions can be closed electronically, and this does not take much time.