AOTC - Computing Parent's Home Support Costs For Child, AOTC, refundable portion of credit

[orcus]

How does the child, under 24, answer, "Yes, I provided over half of my support with earned income", which triggers an extra $1,000 AOTC refundable tax credit in TT, if marked yes.  My AGI is over to claim AOTC.

Child earned $20K in W-2 income

I have their support thus far at $35K (tuition/room/board/recreation), which they paid from their investment account (income was deposited to this account) and this also includes medical that I cover for the whole year.

They live at home and have car use for breaks, holidays, and summer, and that is a component of support in addition to the above.  Child is physically living at home and using car at 105 days out of 365 days.  If I use 12 months of FMV rent/home/car costs for their share, total support is over $40K, if I prorate to the 105 out of 365 days, then total support is under $40K.   Thus, this choice impacts how to answer the support question above in TT.

I can't find any guidance, other than some other replies on this, they are assumed to be living at home, and temporarily at school.   But it doesn't seem right if they are paying for room and board for 260 days, and I'm including like support, room and board, in effect, for those 260 days, it's double dipping and inflating true support.

What's the correct way do this?

[Vanessa A]

When a child is away at college, they are considered still to be living at home.  This means, that you are still maintaining their home so that is part of their support even when they are not there so you do not remove days that they are temporarily away at school.  If they are not coming back home and that place does not need to be there, then you would not include it in their support, but if they keep all their stuff they don't take to college with them and come back home, then although it is in a sense double dipping, it is accurate.  

Think of it the same as if you are traveling and paying for a hotel room, you can't stop paying your mortgage while you are in the hotels so the mortgage and home expenses do not go away or change due to you being temporarily away from home.