The current account records all international flows of goods, services, income, and transfers. It equals the change in a country's net foreign asset position. Current and capital accounts sum to zero.
Show balance of payments structure: current account (trade + income + transfers) and capital account (financial assets). Use examples showing deficits matched by surpluses elsewhere.
The current account is one of two main components of the balance of payments — your hard prerequisite — which records all economic transactions between residents of one country and the rest of the world. The current account covers flows of goods, services, primary income (investment income and wages paid across borders), and secondary income (transfers like foreign aid and remittances). The most familiar component is the trade balance: exports minus imports of goods and services. When a country exports more than it imports, it runs a current account surplus; when it imports more, it runs a current account deficit. But the trade balance is only part of the picture — a country can have a goods trade deficit but more than offset it through services exports or investment income.
The accounting identity that connects the current account to everything else is what you studied in balance of payments: the current account and the capital and financial account must sum to zero. Every current account deficit must be financed by an equal capital account surplus — foreigners must be accumulating claims on the deficit country (lending money, buying assets, or accepting IOUs). A U.S. current account deficit means Americans are buying more from the rest of the world than they're selling, and the counterpart is that foreign entities are acquiring U.S. assets — Treasury bonds, real estate, companies. The current account deficit is literally the change in the U.S.'s net international investment position: running a deficit means U.S. net foreign liabilities are growing.
A critical intuition from national income accounting (your trade balance prerequisite) is that the current account equals the gap between domestic saving and domestic investment. Algebraically: CA = (S − I) for the private sector plus the government's fiscal balance. A country that invests more than it saves must borrow from abroad — it runs a current account deficit. This reframes the question "Is the deficit a problem?" as "Is the excess of investment over saving a problem?" For a developing country financing productive capital formation with foreign funds, a deficit may be entirely healthy. For a country running a deficit because it is under-saving (e.g., large fiscal deficits), sustainability concerns are more warranted. The current account balance is therefore not an independent phenomenon — it is the macroeconomic residual of saving and investment decisions.
Persistent deficits are sustainable as long as the country can service its growing foreign liabilities — which depends on productivity growth, the return on the assets being built with borrowed funds, and the confidence of foreign lenders. The U.S. has run current account deficits for decades without crisis because foreigners value the liquidity and safety of dollar-denominated assets (the "exorbitant privilege"). Countries without this reserve currency status face harder constraints: persistent deficits can eventually trigger sudden stops in capital flows, forcing painful adjustment through exchange rate depreciation and domestic demand compression. The current account is thus a key variable for assessing external vulnerability, but its interpretation is always context-dependent.