J.W.
Ours states that college will be based on the tuition of the University of Missouri Columbia and it is divided by the percentages set in the decree. This way one can't force the other to pay for Harvard when the other can't afford it. So when our oldest daughter went to college with her scholarships her tuition at Xavier was less than Columbia so we split it by our percentages.
So far as gas money goes come on! That is like saying you want to dictate a percentage of clothes. I don't even pay for my kids gas, they want to drive that is their expense. If I did it would fall with if they ask me I give or I say no, same with my ex.
I say this because you don't want to write so much in there you end up with spoiled brats that get everything without earning it. I mean, think about it, what if you were still married, would you actually be filling your child's tank?
Just don't put too much in there because it is all enforceable against you as well, it limits your ability to be rational. I had to fight with my ex the beginning of this summer because we have teens, they like to sleep in. Our decree said we transfer at 8:30 in the morning. So you want me to wake them up and deliver two really pissed off kids or how about I drop them off right before bed and you do the same? First thing out of his mouth, what does the decree say. First thing out of my mouth would get this post removed. He agreed but it is always a struggle to remind him we do still have free will, we can still decide based on what is best for the kids.
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Just throwing this out there we divorced when my youngest was 5, she is going on 13. It has survived two through college, one going into high school now, the youngest going to a private high school. We have never modified it. It is like the freaking Constitution, it is a living document so long as we keep working together. It is more of a fall back when we don't feel like being grown ups.
Seven years! and the only thing my attorney has had to do is send a letter to his attorney explaining she is an accountant, I think she knows how the IRS defines a medical expense.