HSA

A health savings account is the only account in the US tax code that is untaxed at all three moments money passes through it. Contributions reduce taxable income and, through payroll, usually skip FICA taxes too. Many HSAs allow the balance to be invested, and gains grow untaxed. Qualified medical withdrawals are tax-free.

Eligibility is the catch. Contributing requires enrollment in a qualifying high-deductible health plan, as defined by the IRS, with no disqualifying other coverage. Whether such a plan suits you is a genuine healthcare decision, prior to the account's tax features.

HSA funds never expire. Some people pay routine medical costs out of pocket, leave the HSA invested, and let it compound for decades, effectively running it as long-term savings with a medical exit that is tax-free at every step. After age 65, non-medical withdrawals are allowed too, taxed as ordinary income. Contribution limits are modest, and receipts need keeping.