What are these accounts?
An HSA is a health savings account. An FSA is a flexible spending arrangement; both set aside money before tax for medical expenses.
What makes an expense qualify?
IRS means Internal Revenue Service, the federal tax agency. As of September 2026, its guidance separates treatment for a diagnosed disease from spending just to improve general health.
Weight-treatment expenses can qualify for treating a particular disease a doctor has diagnosed, rather than for a general wish to lose weight.
Ask the administrator about the proposed treatment and the records it needs.
Is a letter always required by the tax agency?
Ask the person managing your account whether it needs a doctor’s letter explaining why the treatment is needed. As of September 2026, the IRS guidance itself does not require a document called a “letter of medical necessity”.
The person managing your account may still require that letter as proof that the expense qualifies.
What if a programme includes a watch or sensor?
As of September 2026, IRS guidance says health tracking alone does not make a wearable device a medical expense.
The test is whether it is purchased and used mainly to help diagnose or treat a specific disease.
If a programme includes both equipment and care, ask for a separate price for each.
What backs up the answer?
IRS / the reason for care
Weight-treatment expenses can qualify when a doctor has diagnosed a disease that the treatment addresses.
As of September 2026.
Read the IRS medical expense guidanceIRS / mixed-use equipment
A watch or sensor does not qualify just because you use it to track your general health.
As of September 2026.
Read the IRS device explanation