I guess, looking back, we've been very lucky with Nannies in the past. We've had some broad rules about what is and is not acceptable spending, and they've had the common sense to stick to it.
This one, unfortunately, is different. It's not her money, so she's not bothered about spending it. She's just hit me with an expenses bill for Feb of £300 even though she knows we are completely broke atm. (This is after all her and DD1's food is theoretically paid for on Ocado - Ocado bill a whole other area of contention)
A lot of it is mileage. We have a nanny car, but as she is live out it's easier for her to use her own so we pay mileage at the standard RAC rate. So she'll say to me "we're going to Tuesday morning" and it's not till the end of the month when I get the bill that I realise it was £5 admission but £30 mileage there and back because she has driven to the arse end of nowhere to meet up with non-local friends of hers.
Obviously I have to put in some budgetting rules for her, but I don't know where to start because I've never needed to in the past. What does everyone else do?