1) Added assessment 2) Added charge 3) Added levy 4) Additional charge 5) Additional levy 6) An affordable extra 7) Burdensome additional levy 8) Extra charge, of a sort 9) Extra levy 10) French word used in English 11) Income tax 12) Levy an extra tax on 13) Levy on top of a levy 14) Onerous extra levy 1) Supertax 
A surtax may be a tax levied upon a tax,{huh|date=November 2012} or a tax levied upon income. ==United Kingdom== In 1929, Supertax (which had been introduced in the Finance Act 1909 at the rate of 6 old pence in the pound (2.5%) on incomes over 5000 per year) was renamed Sur-tax. By 1934, the rate was variable from 1 shilling to 7 shillings and si...
• (n.) An additional or extra tax. • (v. t.) To impose an additional tax on.
A tax added to the normal tax paid by corporations or individuals who have earned income above a certain level.
Related
Sur'tax noun An additional or extra tax. Sur·tax' transitive verb To impose an additional tax on. 
[n] - an additional tax on certain kinds of income that has already been taxed 2. [v] - levy an extra tax on, such as a luxury tax on items that cost more than a certain amount
surtax 1. An additional tax on certain kinds of income that has already been taxed. 2. A tax levied on corporations, or individuals, after net income has exceeded a certain level. 3. Etymology: from French surtaxe; from Old French sur-, 'over' + taxe, 'tax'.
supertax noun an additional tax on certain kinds of income that has already been taxed
an additional or extra tax on something already taxed. · one of a graded series of additional taxes levied on incomes exceeding a certain amount.