The tip for a cleaning lady at Christmas time depends on a few factors. First, it's important to consider the quality of service you received. If the cleaning lady did an exceptional job, it would be appropriate to give a generous tip. Second, it's also important to consider your own financial situation. If you can afford to give a larger tip, it would be appreciated. In general, a tip of 15-20% of the total cost of the service is a good guideline.