If you have a full-time nanny, you should gift them with between a week's and a month's pay, plus a gift. Meanwhile, childcare finder Care.com says one week's salary is the norm but acknowledges that some families give more or less. Of course, this depends on a number of factors, including your financial situation, the number of children you have, the demands of your nanny's job, and how long they've worked for you. If any of these numbers are higher than average, then it's wise to consider giving more than just one week of extra pay.
This rule also applies to other full-time domestic help, such as a personal caregiver or cook.