1. An additional tax on certain kinds of income that has already been taxed
   "High earners were subject to a surtax on their investment income";
   - supertax

1. Levy an extra tax on
   "surtax luxury items that cost more than $1,000"

Derived forms: surtaxed, surtaxes, surtaxing

Type of: income tax, tax

Encyclopedia: Surtax