# HOW COME SOME PEOPLE PRESENT THE TAX MULTIPLIER AS -MPC/1-MPC, WHEN OTHER PRESENT IT AS MPC/1-MPC?I ALWAYS SEE ONE FORMULA WITH A NEGATIVE AND THE OTHER WITHOUT A NEGATIVE MPC ON TOP OF THE...

HOW COME SOME PEOPLE PRESENT THE **TAX MULTIPLIER** AS **-MPC/1-MPC**, WHEN OTHER PRESENT IT AS **MPC/1-MPC**?

I ALWAYS SEE ONE FORMULA WITH A NEGATIVE AND THE OTHER WITHOUT A NEGATIVE MPC ON TOP OF THE FORMULA.SO, WHICH IS THE CORRECT ONE? OR ARE THEY BOTH CORRECT? EXPLAIN.

*print*Print*list*Cite

### 1 Answer

If you have seen the second one of these that you mention (the one with a positive MPC on top of the fraction), I do not believe it could possibly be correct. The reason for this is that the tax multiplier **must always** be negative.

Think about it -- if taxes go up, do we get more aggregate demand? No -- we get less. So if taxes go up, the change in AD must be negative.

When we use the tax multiplier, what we are saying is this:

Change in taxes times multiplier = change in AD.

So a positive change in taxes (they go up) has to equal a negative change in AD. Mathematically, that means the multiplier must be negative.

If you have a positive MPC on the top of your fraction, the multiplier will be positive and that can't be.