This frequently arises in Medicaid and Veterans Administration Improved Disability/Improved Death Pension cases. In the Medicaid context, many states have very specific criteria to qualify as a personal services contract. In the VA situation, you need a care plan, 24/7, devised by an MD, RN or LPN. Then the family members can carry out the plan, provided that they have telephone contact with the MD, RN or LPN at least monthly. If these requirements are met, the money spent can be deducted to determine eligibility for the VA Pension
If the elder person requires the care because of certain physical or mental disabilities and the care is prescribed by the physician, then the requisites for deductibility are met.
I sometimes give clients a form for their physician to fill out that states the client is in need of the care from a physical or mental standpoint and that the doctor prescribes that care for the client/patient.
that should suffice, but consult with your tax professional.
of course, the aide would have to be paid "above the table." While I never recommend clients pay aides "below the table," I would be ignoring reality if I didn't point out that many people pay aides under the table.
If you aren't paying the aide legally, you could not deduct the payments as medical expenses.