That's complicated.
First, you can deduct medical expenses as an itemized deduction, for yourself, your spouse, your dependents, or someone who could be your dependent and is only disqualified by their income or by filing a joint return with a spouse.
In the case of a parent, you can claim them as a tax dependent if you pay more than half their total living expenses (shelter, medical, food, clothing, travel, etc.) AND their taxable income is less than $4200. If they have more than $4200 of taxable income but you still pay more than half their expenses overall, then they are not your dependent but you can still deduct medical expenses you pay on their behalf. (Remember that social security is not taxable, but does count as money they provide toward their own support.)
Then, which expenses are deductible?
The bottom line is that if the parent is competent, and moved to assisted living for convenience, then the only expenses that count as deductible medical expenses are those rendered by a medical professional to treat, cure or mitigate a disease or condition of the mind or body--prescriptions, nursing check, and so on. Shelter, food, and personal care expenses are not deductible.
However, if your parent is in a nursing home primarily to obtain medical care, then you can deduct all expenses, even for food, laundry and so on, and don't need to split out the medical and non-medical expenses.
There was also a recent change in the law relating to dementia and Other chronic illnesses. A person can be certified by their doctor that they are chronically ill if they are unable to perform 2 or more activities of daily living without assistance (eating, toileting, transferring, bath, dressing, or continence); or if they require constant supervision because of cognitive impairment, to prevent them being a danger to themselves or others. In that case you can count their expenses as deductible medical expenses even though they may not all be considered "medical" care. However, for this to be allowed, the facility must be providing care according to a plan of care prescribed by a licensed health care provider. (This means a doctor, nurse, or social worker must prepare a plan that outlines the specific daily services the resident will receive.)
