This question seems to come up a lot, so I figured I'd post the actual law regarding waiting for work and when you do or do not need to be paid. This is according to the Fair Labor Standards Act, which I encourage everyone to at least skim through.
Generally, if you have issues with an employer, you can just quote something like this and they will stop hassling you (ie. “according to the FLSA…”). Once they know that you know your rights, they usually aren't going to push it.
From the department of labor website here: https://webapps.dol.gov/elaws/whd/flsa/hoursworked/screenER78.asp (see also Off-Duty Waiting Time and On-Call Time)
FLSA Hours Worked Advisor
On Duty Waiting Time
When your employee is waiting for work to do, for repairs to be made, etc. while on duty, he or she is engaged to wait and the time is hours worked.
For example:
A receptionist who reads a book while waiting for customers or telephone calls.
- A messenger who works a crossword puzzle while awaiting assignments.
- A fireman who plays checkers while waiting for alarms.
- A factory worker who talks to fellow employees while waiting for machinery to be repaired.
- A waitperson in a restaurant waiting for customers to arrive.
The rule is the same for employees who work away from the plant.
For example:
- Time spent by a repair person who has to wait for his or her employer’s customer to get the premises ready probably is hours worked.
- Time spent by a truck driver who has to wait at or near the job site for goods to be loaded or unloaded is probably hours worked.
- Time spent by a bus driver who reaches his or her destination and while awaiting the return trip stays with the bus to guard the bus and any items left on the bus is probably hours worked.
In each of these situations, the employee is engaged to wait and the time is hours worked. Waiting is an essential part of the job.
The time is hours worked even though your employee is allowed to leave the premises or the job site during such periods of inactivity. The period during which the inactivity occurs is unpredictable and usually of short duration. In either event, your employee is unable to use the time effectively for his or her own purposes. Your employee's time belongs to and is controlled by you, the employer.