There is one account in the American tax code that is never taxed. Not when the money goes in, not while it grows, not when it comes out. Most residents have access to it and walk right past it.
It is the Health Savings Account, and it wins on all three legs at once. A traditional 401(k) gives you a tax break going in, then taxes the withdrawals. A Roth flips that: taxed going in, free coming out. The HSA is the only account untaxed at every step, as long as the money goes to care: in pre-tax, growing tax-free, and out tax-free for any qualified medical cost (visits, prescriptions, dental, vision). Fund it through your employer's payroll and it skips the 7.65% payroll tax too, which no 401(k) or IRA does.
So why does almost no resident use it? The gate. You can only contribute in a year you are enrolled in a high-deductible health plan, and that high deductible scares people into the safer-sounding plan by default. For 2026 the plan must carry a deductible of at least $1,700 for single coverage or $3,400 for a family, and you can then put in up to $4,400 single or $8,750 family.
Check before you contribute: the HDHP alone isn't enough. A spouse's non-HDHP plan that also covers you, a general-purpose FSA on either of you, enrolling in Medicare, or being claimed as a dependent will each disqualify you.
Here is why that high deductible is often the wrong thing to fear. You are likely young and healthy, with a year of low medical use. If you were never going to hit the deductible anyway, the high-deductible plan is just the cheaper plan that unlocks the best account in the tax code. And unlike a Roth IRA, the HSA has no income limit, so it stays fully open the day you become a high-earning attending. It is the one tax shelter that never phases out.
The move, if the plan fits you: contribute, then actively move the balance into investments (most HSAs leave it sitting in cash) rather than spending it on copays. Let it compound across the years you barely touch it. Used that way the HSA quietly becomes a second retirement account. (Using it as one is its own future issue.)
One caution. If you expect a heavy medical year — a planned pregnancy, surgery, an ongoing condition — run the real numbers, because the low-deductible plan can win. Choose on your expected spending, not on the scary deductible.
Almost no one opens it: the only account the tax code never touches.