Ready2Change hit the nail on the head. You apparently agreed to pay for 70% of childrens' expenses, and allow submissions 11 months late. That's big money. She is probably as annoyed she has to itemize them, as you are annoyed at having to review $4 expenses and itemize them yourself. If itemization is frustrating you, the simple thing to do is to end it as he proposed above.
Itemize your childrens' expenses this past year. Now, what is the $SUM you owe for 11 months? She would probably be amenable to dropping the itemization and simply paying ($SUM/11) * 5% extra each month.
The only expense in my agreement where my ex and I split costs are mandatory medical expenses. These could be urgent and costly. In our agreement, receipts must be submitted within 30 days.
If you are paying more than child support guidelines, talk to your attorney.
