Savings identity or the savings investment identity is a concept in National Income Accounting stating that the amount saved (S) in an economy will be amount invested (I). More specifically, in an open economy (an economy with foreign trade and capital flows), governmental borrowing plus private investment must equal private savings plus foreign investment. In other words, investment must be financed by some combination of private domestic savings, government savings (surplus), and foreign savings (foreign capital inflows).

Note that this is an "identity", meaning it is true by definition. This identity only holds true because investment here is defined as including inventories. Thus, should consumers decide to save more, and spend less, the fall in demand would lead to an increase in business inventories. The change in inventories brings savings and investment into balance without any intention by business to increase investment.