Web: Setup > Services > Spiff
A spiff is a bonus paid for selling a particular service. When a service is marked 'Spiff', its service rate is paid to the techs on that line. It is split evenly across the commission-eligible techs, and it beats a technician's own rate.
Set a commission on the service first. Until then the spiff shows 'Inactive until this service has a commission', and the cell says 'Set a commission first'.
Example: A service pays a Fixed $30 spiff and two commission-eligible techs are on the line. Each earns $30 / 2 = $15.