What Are Twin Deficits — The Link Between Fiscal and Current Account Deficits
Why is the U.S. always said to carry 'two deficits'? Let us unpack this concept—that the household deficit (fiscal) and the external transaction deficit (current account) travel together like twins.
What are the two deficits?
Twin deficits refer to a situation in which one country suffers a 'fiscal deficit' and a 'current account deficit' at the same time.
A fiscal deficit is the government's household deficit. It arises when the government spends more money than it earns in taxes.
A current account deficit is the entire nation's external-transaction deficit. It arises when imports and overseas spending exceed what is earned through exports, overseas income, and so on.
The representative country that experiences these two deficits together is the United States. That is why the term 'twin deficits' often comes up when explaining the U.S. economy.
Source: Wikipedia 'Twin deficits hypothesis.' The reason it is named a 'hypothesis' is explained below.
Why the two are linked — the theoretical path
The twin deficits hypothesis proposes a causal relationship in which 'a fiscal deficit invites a current account deficit.' The connecting path is roughly this.
When the government borrows and spends a lot (fiscal deficit), demand for funds in the market grows and interest rates tend to rise.
When rates rise, foreign capital comes in chasing the high interest. This capital inflow strengthens the home currency (appreciation).
When the currency strengthens, exports look expensive and imports look cheap, so exports fall and imports rise. As a result the current account deficit grows.
In other words, the domino of 'fiscal deficit → rising rates → currency appreciation → current account deficit' is the core of the theory.
Source: New York Fed, Current Issues in Economics and Finance. This path is mediated by interest rates and the exchange rate.
But it does not always hold
There is a reason 'hypothesis' is attached to the name. It is because this relationship does not always hold in actual data.
A representative counterexample is the U.S. in the late 1990s. During this period the U.S. carried a substantial current account deficit, yet the government's fiscal position was actually a 'surplus.' A current account deficit arose without a fiscal deficit, which contradicts the twin hypothesis.
Japan, too, ran a large fiscal deficit in the 1990s but had a current account surplus. That is the opposite direction again.
Why do such exceptions arise? Because the current account is driven not only by fiscal policy but by countless factors—citizens' saving and investment tendencies, the global business cycle, and a currency's special status. In particular, because the dollar is the reserve currency, the U.S. has the peculiarity that even when it runs a current account deficit, the world keeps buying dollar assets, so it does not lead to a crisis.
In conclusion, twin deficits are a 'useful framework of thought,' but not a law that holds for all countries and all periods.
よくある質問
Q. Is a large twin deficit a dangerous signal?
For an ordinary emerging market, it can be a warning signal—it becomes fuel for a currency crisis. But a country with a reserve currency, like the U.S., can hold out relatively long even with a current account deficit because the world buys its dollar assets. Even for the same 'twin deficit,' the level of danger differs greatly depending on the country's currency status.
Q. Is Korea in a twin-deficit state?
Korea is a country that has long maintained a current account surplus, so it is not a typical twin-deficit country. However, since the fiscal and current account balances change year to year, figures at a specific point are most accurately confirmed directly through Statistics Korea and Bank of Korea data. This article is a conceptual explanation and does not make definitive claims about the national fiscal state at a specific point.
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