The Laffer Curve for Government Spending
The budget deficit depends upon government spending and taxes. If government bonds are net wealth, and I will presume they are, then an increase in the budget deficit will increase output. It doesn't matter which of the two components change the deficit, government spending can be increased or taxes can be cut, output will go up in either case. So the fact that a cut in taxes stimulates output and raises revenues is not surprising, anything that increases the size of the deficit will have this effect.
For example, consider an increase in government spending. This is, in part, self-financing, just like tax cuts are claimed to be. When government spending increases, output increases by some multiple of the increase in government spending through the expenditure multiplier, and this causes taxes to increase. Therefore, an increase in government spending raises taxes and helps to pay for itself. The correct type of spending on, for example, infrastructure might actually stimulate output so much that it increases revenues by more than the increase in government spending! I doubt that, but it's as easy to make this claim for government spending as it is for taxes through the Laffer curve.
Thus, the fact that revenue increases following a tax cut tells you nothing about tax cuts per se, it simply confirms that deficit spending is expansionary. Here's a graph to illustrate how an increase in government spending can increase revenue:

True or not, it's pretty easy to make these claims. Of course, we can trust the press to fact check such claims thoroughly rather than just report what they are told, can't we? Paul Krugman has something to say about that in the post that follows this one.
Posted by Mark Thoma on Friday, December 2, 2005 at 12:33 AM in Budget Deficit, Economics, Taxes | Permalink | TrackBack (1) | Comments (3)

Yes, there a lot of governments around the world that have some experience in deficit spending. Many of them would really wish budget deficits to increase output and finance itself. May be this is what Europe should try. To hell with the stability pact. But I think that they have already tried this. It is really easy to make these claims.
Posted by: TI | Link to comment | Dec 02, 2005 at 07:10 AM
Are we all really Keynesians yet?
Posted by: dryfly | Link to comment | Dec 03, 2005 at 09:45 AM
hi im doin economics for A levels can u post my some of the things that u think are relavent to my studies and the things that would help me wiv my studies
thank you
xxxxxx
Posted by: roxy | Link to comment | Feb 07, 2007 at 03:15 AM