I agree, especially because with the time off for Christmas break (almost a month) and almost five months off in summer, she's really not gone that long. Also when I moved her in, we did a grocery/supplies shop that cost about $100, and I expect I'll take her for groceries a couple times a month. But I know it's customary to reduce CS while the child is away, I'm just trying to see what's fair in my situation.
Depending on your incomes and expenses he would be required to pay something depending on what the judge thinks. My husband’s ex is fighting for 1/3 support but her income is double his and she lives outside her means. The judge at their motion said no support.
If she is in residence with a meal plan then the question may be why are you buying her groceries? She has a meal plan. He will argue that she has either a meal plan or groceries not both. (Mcdreamy will have something to say but this is from the judge we had).
The next question is if she is coming home so often (even to work), why did she go away to school and incur the additional costs? Could she not go to school closer to home and commute or find a job in the school town and not go home. That will be the next argument.
As for grants, they can either come off the top or be kids portion of the expense. The judge at my husband’s motion clearly stated that it would not shock the conscience of the court for kid to pay a third of the expenses and get a loan to cover that. (I should also note that this judge has presented on cs and share of expenses for kids in post secondary for years through the Bar association, Im not saying he is right, Im pointing out what he said from the bench.)
At this point you need to get a bit organized and start preparing yourself for a motion. Send him an email advising him that you have already reduced child support below table and have not requested an update based on income against the Federal Child Support Guidelines. That since he has decided to unilaterally reduce support already below table and determine an unreasonable split of expenses you are now seeking proof of his current income and a proportionate split of eligible expenses.
If he balks, start a motion to change. You will need to explain why you waited to seek a change and also respond to the arguments against it that I listed above. You will also need to defend why you spend so much additional money when there are meal plans or post grad programs closer to home when kid travels home so much. This was an argument my husbands ex lost—kid needed to be at home, well then why did they go away to school at an additional expense of $10,000 per year.