I think that the issue boils down to - do you only pay for her gas when she is driving your kids and related errands? Do you pay for her gas for her social life? The PP who said that she calculates the kids weekly mileage only pays it has made it clear that the au pair is responsible for any mileage that she uses for going out, etc.

I think that the OP's au pair was handing the HM a bill for not only the kids related mileage, but also her own mileage when she went out over New Years.

Why can't you fill up the car with gas and then you won't have to worry about your AP's taking advantage of you. This seems so silly to me. If you are worried about your AP lying to you about a few bucks, how can you trust them with your children and living in your homes?

Is there a question?

I calculate the amount of gas each week the car will be needed to drive the kids around and give that money to the AP. Then she's in charge of filling it up. That way, she can't take advantage of it.

Okay?

I was handed a hand written receipt for $40 of gas, purchased on Monday. It had an amount of $30 dollars written on it, but that was crossed out. Our au pair has driven the car in total about 10 miles with the kids this week. There is probably about $15 dollars worth of gas left in the car. Given that she did take the car on New Years Eve and Day; but I don't think she went that far. I have a feeling that she's lied about the amount of gas purchased. Which irritates me.

Additionally we do ask that she replace the gas that she uses, but that is on the honor system. I guess I will just remind her of this and ask her to print receipts.