noun / verb
surtax
SUR-taks/ˈsɜːrtæks/
An extra tax added to an existing tax.
The city adds a surtax to the existing hotel tax.

Etymology
Here sur- places one tax “over” another: a surtax is an extra levy on something already taxed. The prefix marks an addition to the existing charge.
In context
According to Belicheck the Patriots organization is unable to compete fiscally with teams and other states that do not have an income surtax to contend with
More examples
- High earners pay a surtax on top of their regular income tax.
- The proposal raises the surtax from two percent to three percent.
- The state surtaxes income that is already subject to federal tax.
Forms
surtax · surtaxes · surtaxed · surtaxing