Sources of information on the balance of payments are:
Customs statistics – transactions with goods registered by the customs authorities. The customs authorities record in their reports the value of consignments of goods exported and imported into the country, as they are declared by suppliers. The main errors may arise in connection with the overestimation of the price of imports (in order to transfer currency abroad), understatement of the export price, registration of exports or imports not at a contract price, but at a reference price, unregistered trade (smuggling, cross-border trade), consignment trade. Often, trading on credit is recorded as a regular trade for cash, and not as a record parallel to obtaining a trading credit. Gifts, both private and interstate grants, may not be included in trade statistics at all; Statistics of the monetary sector – data on foreign assets and liabilities of the banking system (Central Bank and commercial banks). Errors may occur due to the fact that the reporting of many countries may not make a distinction between the operations (deposits, loans, etc.) of residents and non-residents, do not take into account the operations of non-residents in national currency, do not take into account exchange rate fluctuations when assessing foreign exchange reserves held in the form of foreign securities; External debt statistics – data on reserves, flows and payments on public and private external debt of residents to non-residents. Data on external debt can be accumulated either by the Ministry of Finance or the Central Bank. However, often to double-check these data, it is necessary to use the statistics of countries that provide loans to this state, or the statistics of international organizations, primarily the World Bank, the OECD, the Bank for International Settlements. Problems may again be related to the lack of a breakdown between residents and non-residents in the reporting, for example, on domestic debt; Statistical surveys – data on international trade in services, labor income, remittances of migrants, which are usually of an estimated nature, since they are collected through periodic surveys of travel companies, hotels, migration bureaus. The most difficult is the collection of information on direct and portfolio investments, investment income and debt servicing by the private sector, as such data are also estimated on the basis of only a sample survey of enterprises. Errors can occur due to the fact that part of the direct investment is carried out in kind – in the form of deliveries of machinery, equipment, technology, which can be registered as ordinary trade. Statistics of operations with foreign currency. This data is of particular value in those countries where exporters are required by law to exchange all foreign exchange earnings from exports in the central or other authorized banks.