If my maid is not paid for washing my mother's flat, is it still illegal?

The Work Permit Office requires an FDW to declare that she will not work for anyone other than the employer whether with or without pay. The FDW declares:

• "I shall work only for the employer and in the occupation specified in the work permit or visit pass."
• "I shall not work for any other person in any capacity, with or without monetary payments."

See conditions of Work Permit/Visit Pass for Foreign Worker, Conditions 2 and 3