You've fought over everything else, so when it comes to divvying up the shared expenses after a divorce, you know that it's time to put on your fighting gloves. Though you both want what's best for your children, it can often seem like you're from two different planets. One person's "necessary expense" might seem like a "frivolous extra" to the other. Work things out as civilly as possible to avoid stressing the children.
Food, shelter and clothing are the most basic things that your children will need, so it's natural to find a way to split these up. Typically, these are going to be the costs that go into the divorce settlement and child support plan. Maintaining two separate residences can be expensive. You may not be able to stay in the home you shared.
College isn't going to pay for itself and helping your child get there costs money as well. Educational costs should also be shared by divorced parents. These costs might include school supplies, school fees, private school tuition and contributions to a college savings plan. In some cases, a grandparent might step up and offer to pay for something like tuition costs, but this shouldn't exempt either parent from paying for the other essentials.
Health insurance premiums, co-pays, co-insurance and other medical expenses all are necessary expenses that parents should share. In most cases, one parent will keep the children on his or her employer's insurance plan, but there's a cost associated with this. Try to put aside your differences and work out a fair method for splitting the costs. If you're not simply adding all the costs and dividing them up, you might have one parent pay the premiums, while the other pays for everything else.
The other shared expenses are pretty basic. Everyone can agree that they are necessary to some point, though some might argue that a private school education or new clothes every month are "extras." The issues get a bit more cloudy when it comes to the other expenses in your child's life, such as sports equipment and fees, dance or music lessons, pets and outings with friends. These expenses are typically shared expenses, though the line may not be as 50/50 (or 25/75) as other expenses. For example, the parent who's hoping that the son will be the next football all-star might be more willing to foot the bill for those expenses if the other parent was hoping for a classically trained musician. Again, when working this out, it's best to put on your grown-up hat and come up with a way that works for you both and especially for your child.