Medicare Part A Backdating Can Turn HSA Deposits Into Taxable Excess Contributions
When Medicare Part A enrollment is backdated up to six months, any health savings account contributions made during those months become excess contributions. Those deposits lose their tax deduction and face a 6% excise tax for each year they remain in the account. To avoid the problem, savers should stop HSA contributions six months before applying for Medicare or Social Security.
Medicare Part A, which usually has no premium, can begin as many as six months before a person applies, though not earlier than the month they turned 65. This retroactive rule dates to 1983. The IRS counts those backdated months as Medicare coverage months, so HSA deposits made then are not allowed.
Because Social Security retirement benefits at 65 or older automatically trigger Part A, the same issue can arise without a separate Medicare application. Savers who keep contributing to an HSA after their birthday month may later learn that part of their deposit is an excess contribution, losing the deduction and facing an annual 6% excise tax.
Older workers who delay Medicare while contributing to an HSA may be most affected. A backdated Part A start date could turn recent deposits into excess contributions, reducing expected tax benefits and adding an excise tax that may grow each year. This may create unexpected costs for retirees and complicate financial planning, especially for those who claim Social Security later. Clear guidance to pause HSA deposits six months before enrollment could help some avoid the issue.