The National Minimum Wage
[ch 10: page 75]All workers who contract (whether or not in writing) to provide personal services to another person or organisation must be paid at least the National Minimum Wage (NMW). They should get the NMW whether they are in a permanent job, a short-term or zero hours contract or working for an agency, and even if they work at home.
Piece-work pay should be paid at the NMW rate.
There are a few exceptions, including the genuinely self-employed (see Chapter 2) and genuine volunteers (see Chapter 9).