I am doing my grandmother-in-laws taxes. She moved to assisted living in late August of 2017. She was supposed to move in during July, but due to their restrictions, she could not until 8/30. But, she had to pay for July and August to secure her spot at this long term care facility. My MIL thinks I should only deduct the cost of care for September-December, because that when she was really there. That's fine, I'm sure the IRS wouldn't complain, and it is the conservative thing to do. But I do think we could make a case for deducting July-December, since expenses are deductible when they are paid, not incurred. Well, I suppose the expense was incurred in July and August when the facility required payment, but services were never received. So we have paid expenses, not received, and possibly incurred.
Can anyone point to any guidance or prior cases that would support taking the cost of care as a deduction for July and August?
(Yes, I know about AGI limits related to medical expenses.)