Absorption is total domestic spending on goods and services, excluding exports. In macroeconomics, it is usually defined as consumption plus investment plus government purchases, and it is useful because it links domestic spending to output and the external balance.
Core Identity
In an open economy:
\[ A = C + I + G \]
and national income can be written as:
\[ Y = A + (X - M) \]
So net exports equal output minus absorption:
\[ X - M = Y - A \]
If a country absorbs more than it produces, it usually runs a trade deficit. If it produces more than it absorbs, it usually runs a trade surplus.
Why Economists Use The Concept
Absorption is central to the absorption approach to balance-of-payments adjustment. The idea is that a currency devaluation or other policy change improves the external balance only if it raises output relative to domestic spending, or lowers spending relative to output.
That is why exchange-rate policy alone may not be enough. If households and governments keep spending aggressively after a devaluation, imports can remain high and the current account may not improve much.
Practical Interpretation
Absorption is close to domestic demand, but the external-balance framing is what makes it especially useful in international macroeconomics. It helps explain:
- why current-account deficits reflect spending in excess of production,
- why fiscal tightening can sometimes improve the external balance,
- why growth driven by domestic demand can widen imports.