fiscal drag
From Longman Business Dictionaryfiscal dragˌfiscal ˈdrag noun [uncountable]ECONOMICS when rising incomes mean that the government receives increasing amounts of tax, as people move up into higher TAX BRACKETs (=levels of income with a particular tax rate). Taxes have to be adjusted to take account of this, if it is not to have an effect on the economy as a wholeIf we do not cut taxes, the normal process of fiscal drag means that the tax burden rises over time.