While a tip is never expected or requested, they are always appreciated by the cleaner. You can offer a cash tip or simply add it to a recurring bill. If you choose not to tip a cleaner, they will still go above and beyond for you and ensure the house is as clean as can be, so never feel that they will do a bad job if not tipped. Your cleaner is committed to offering the highest level of service possible.
It is generally recommended to offer a small amount at each cleaning. On average 10 to 20, however, any amount is always appreciated.