THE INTERACTION OF DIFFERENT TAX FORMULAE
§ 1. WHEN a tax scheme consists of more than one tax formula, the revenue yielded by it is not, in general, equal to the sum of the revenues which would have been yielded by each tax formula, had it been imposed by itself. The relations involved being somewhat complex, I propose in the following paragraphs to analyse them briefly.
§ 2. First, when a given revenue is being collected and used up by the government--not merely retransferred, e.g. in interest, to the public 1--the fact that this quantity of revenue is being raised, irrespective of the manner of its raising and so, of its announcement effects, is liable to modify the yield of further taxes, if such are imposed. Some sorts of further taxes are, indeed, unaffected. Thus a poll-tax, or a tax of so much per acre on all land, or a tax proportionate to true rents, will yield the same revenue whether much or little revenue is being raised contemporaneously in other ways. Again, the yield of taxes on earned income will not be affected; for they are normally assessed on income reckoned prior to any payments made out of it to meet other taxes, so that these payments do not directly affect the magnitude of the assessed object. On the other hand, any ordinary commodity tax will yield less revenue when the taxpayers are than when they are not impoverished by other taxation. So will taxes on investment income and death duties, because impoverish-____________________