My ex and I equally split the cost of school lunch, all school and activity fees, any extracurricular activites and any expenses like cell phone bills, health insurance premiums, health club dues, and medical and dental copays. I also reimburse him for half the health insurance premiums for the kids, since he carries them on his plan at work. I carry my son on my car insurance, so every six months I call Nationwide and they give me two figures: what it would cost to carry me only, and what the difference is when we add my son. My ex pays half that. If I get my daughter a haircut, I pay. If I buy her clothes, I pay. If I buy her a bike, it stays at my house the majority of the time. If I take her to a waterpark or a movie, or if she goes with a friend on "my time", I pay. If it's for school or Girl Scouts or 4-H, we share the expense, regardless of who has her that day. She's taking a Red Cross CPR/First Aid babysitting course on my evening. We share the cost.I buy her the majority of her clothes and personal items simply because it's akward for a 13 yr old girl to have her dad take her to be fitted for bras. Her dad pinches pennies when it comes to anyone but himself, so I also buy her things like hairbrushes and hair ties, because he buys the cheap crap you can't even use without pulling your hair out. I'm sure he fudges the numbers, because he will use any opportunity to "screw" me. If he gets off on having me pay an extra $50 for health insurance when he makes 3 times as much money as me, fine. It's not worth the hassle requiring receipts, but if it got out of hand I would demand it.