Wealth tax uses political capital.

Perhaps the biggest political obstacle to the introduction of a one-off wealth tax is the fact that it is politically costly, yet some of the fiscal benefits that it generates will redound to the credit of future governments – assuming annual payments extend across at least one electoral cycle, and/or the funds are used to pay down debts. Why expend political capital in the pursuit of additional revenue (or lower debt levels) for one's successors? Yet the same objection could be levelled against any significant revenue-raising measure.22 The time-bound nature of a one-off wealth tax means that revenues are likely to fall primarily to the tax-introducing government, depending on the timing of the tax and the length of the electoral cycle, as well as on factors such as inflation and any interest charges applied to tax liabilities paid by instalment.