Cyberyeti, on 2012-August-01, 04:24, said:
Every tax needs people to administer it, which is a cost. There is also an opportunity cost, since the individual being taxed would presumeably have spent it in the way most pleasing to him, tax on gains if you spend it in a way less pleasing to him, which is a cost. Although its also "not real" as presumably someone is getting a benefit they could not otherwise afford.
To put it in perspective, the IRS in america costs about 14bn$, or roughly 1% of gdp. I think anything up to about 3% of gdp on administering tax is quite normal.
But yes, there are any number of ways a government can spend money where the return on investment is higher than the cost of administering the tax, which is probably why having tax takes between 30-50% don't have a huge or reliable effect on gdp growth.