Charleston had a
system whereby a slaveholder could pay a license fee, good for one
year at a time, on a sliding scale based on the slave's primary
occupation. In return, he would receive a copper tag or badge for
each slave registered containing four pieces of information: the
city (Charleston), a serial number, the date (year), and an
occupation.
The master was then allowed to hire that slave out to
private individuals, businesses, or even the municipal government
with the proviso that the slave would wear the badge at all times
when on one of these hire-out jobs and that the slave could only
perform the function he was licensed to perform.
Who benefited from
this? The city made thousands of dollars a year in badge fees; the
slaveholders made extra money for hiring out slaves that they had
no work for at the time; the slaves themselves were often allowed
to keep part of their outside wages and, as a bonus, they were
given a certain amount of freedom in exchange for their skills.
Read more here
Slave Badges and the Slave-Hire System in Charleston (The American Dream)