As you seem to be aware, charges for an assisted living facility are generally not tax-deductible as medical expenses. You can only deduct those expenses that are for nursing care. The care does not have to be provided by a nurse but it must be the kind in type of services usually provided by nurses.
if the person is chronically ill, you can deduct the entire cost of assisted-living as a medical expense if you meet three tests.
1. The person is chronically ill, meaning they have been certified by a doctor to have a chronic illness that will last at least one year or will lead to death, or the person has a cognitive impairment which means that they will be a danger to themselves or others unless under constant care.
2. The person requires assistance with two or more activities of daily living. Activities of daily living are eating, toileting, continence, transferring, dressing, and bathing.
3. The care is provided according to a written care plan developed by a medical professional or qualified social worker that is reviewed and updated at least once a year.
To your specific question, generally speaking, things are only deductible when they actually happen. If you don’t have a written care plan until March 1, then expenses before March 1 would not fall under that rule. However, I’m sure it is true from a medical point of view that your spouse‘s chronic illness was the same before the plan was written, and the humane answer would be that the care is a qualified expense. I have not seen any tax court cases that cover this specific issue. Most taxpayers are not audited. If you have the bad luck to be audited, it would be up to the individual auditor whether to accept a letter as covering care provided before the letter was written. It might depend on the length of time. I would imagine that you would have an easier time deducting all of your expenses for 2021 if the letter was written in March, 2021, than you would have deducting retroactive expenses from 2020 or 2019 for a care plan only written in 2021.
In the end, I think you will have to take your own informed risk on this.
