The Balanced-Budget Multiplier

In the previous note, we showed that equilibrium GDP is governed by the following:

Ye = x (a -bT + Ig + Xn + G) where b is the MPC. From this relationship, we determined that the "multiplier" for government expenditures is equal to = . Likewise, the "multiplier" for lump-sum taxes is equal to = . More generally, we see from the formula for Ye that D Ye = x (-bD T + D G). What happens if there is a balanced-budget change in government spending and taxes? Substituting D T = D G to find D Ye, we see that D Ye = x (-bD G + D G). Factoring out the common D G from the term in parentheses and rearranging, we find that D Ye = x (1 -b) x D g = D G. That is, the change in equilibrium GDP from an equal change in government spending and taxes is equal to the change in spending. Alternatively, the multiplier for a balanced-budget change in G and T is equal to = x (1 -b) = 1.