## Teaching why the Balance of Payments equals zero.

A HT to colleague Nick Lloyd for this great explanation of the relationship between the current account and the capital and financial accounts. In theory the balance of payments should equal zero and this is one area that students find hard to comprehend. Hope you find it as useful as I did.

The Relationship between the Current Account and the Capital and Financial Account

A few starting points:

1. Gross Domestic Product (GDP) = C + I + G + (X – M)
2. Gross National Product (GNP) = GDP plus Net Income (Income Credits (Yc) – Income Debits (Yd))
3. Saving/Investment Gap (S – I) = Balance on Capital and Financial Account (Capital Outflows (Ko) – Capital Inflows (Ki))
4. Current Account Balance = Trade Balance (X – M) + Net Income (Yc – Yd)
5. National Savings = GNP – (Private Spending (C) + Government Spending (G))

Now:

GNP                                      =               GDP + (Yc – Yd) =  C + I + G + (X – M) + (Yc – Yd)

GNP – (C + I + G)                 =               (X – M) + (Yc – Yd)

GNP – (C + G) – I                 =               (X – M) + (Yc – Yd)

S – I                                    =               (X – M) + (Yc – Yd)

Balance on Capital & Financial Account               =               Balance on Current Account

Another way to arrive at the same conclusion:

Assuming freely floating exchange rate is in equilibrium:

Demand for Currency = Supply of Currency

Demand comes from:     X + Yc + Ki

Supply comes from:        M + Yd + Ko

Thus when the forex market is in equilibrium:

Demand                         =               Supply

X + Yc + Ki                    =               M + Yd + Ko

(Ki – Ko)                        =               (M – X) + (Yd – Yc)

Balance on CFA               =               Balance on Current Account

So, if as a nation you earn more than you spend (current account surplus), you are in effect lending to the rest of the world (exporting savings) by accepting IOUs in the form of your increased holdings of foreign assets (shares, land, government bonds, etc.)

If as a nation you spend more than you earn (current account deficit), you must borrow from the rest of the world (import savings) in the form of increased foreign holdings of your domestic assets (shares, land, government bonds, etc.)