Be absolutely sure you are on firm ground with the social security issues. When to take benefits and whose to take is a huge financial decision--it's crucial that your MIL gets it right. Also, it is very hard to know whether she will really enjoy being the nanny or not. I started doing it for DD and s-i-l. The children are 4, 6, and 8. I found that as much as I wanted to love the role, that I do not. There is such a difference in culture and values...such different ideas about child-raising...that I have agreed to play the full role for this oncoming school year, but after that, when all three will be in elementary school and logistics should be easier. for the parents..I am resigning. (Let me say that I do not accept any money for the childcare...and for me that is fine...they try to pay me, but I won't take it.) We all get along well, and I think it would have haunted me forever if I had not tried this. But based on the way they raise their kids...I'm not comfortable being this involved on a day to day basis, and I'll be outta here. Also remember that working for you is going to tie your MIL down in a major way. Her own interests and activities, visits with friends, travel...will be curtailed. Plus there will be times when she doesn't feel well and needs some sick time off. Be sure that you have back-up systems in place.