Any serious efforts to improve the tax system inevitably comes up against dubious assertions that such changes won’t improve economic growth or reduce tax avoidance, and will therefore not be “revenue neutral” but will simply increase deficits and debt for no reason.

The easiest way to block growth-oriented tax reforms is to insist that any such changes must be “revenue neutral” even in the short run. However, that goal typically relies on uncritical acceptance of dubious estimates of (1) how much “baseline” revenue the existing system will bring in over 10–20 years, and (2) how much revenue a better tax system would bring in under the conventional and official assumption that higher or lower marginal tax rates on added income have no significant effect on anything.

As Harvard economist Greg Mankiw importantly notes, “A key question is how revenue neutrality is to be judged.” 

Before Congress could even attempt to be “revenue neutral” they must first have credible estimates of future revenue under the current tax regime. Unfortunately, the Congressional Budget Office and Joint Committee on Taxation have so far provided only incredible projections. 

Here are links to my critiques of official revenue projections for corporate and individual income taxes. 

For Congress to judge “revenue neutrality” on the basis of these extremely flawed hyper-static CBO/JCT estimates would be economically and fiscally irresponsible.