Orientation hands you a benefits packet, and somewhere inside it is a retirement plan: a 403(b) or a 401(k), depending on how your hospital is organized. If a match is attached, the hospital adds money to the account when you do. It gets called free money, and it mostly is. What the packet rarely explains is that the match arrives with a clock, and residency is short enough that the clock decides whether you keep it.
Two kinds of money sit in that account, and they follow different rules. What you contribute from your own paycheck is yours the moment it lands. The IRS is unambiguous: an employee's own contributions are always 100 percent vested, which is the plan's term for owned outright. Nothing you put in can be taken back, no matter when you leave, or why.
The employer's share is the part with conditions, and it becomes yours on a vesting schedule. Plans use one of two shapes. Cliff vesting pays nothing for a set stretch, three years at the outside, and then all of it at once. Graded vesting hands over a rising fraction: 20 percent at two years of service, 40 at three, 60 at four, 80 at five, and the whole balance at six. For most private plans, federal law permits nothing slower than those two.
Read that graded schedule against a three-year residency. A resident on that schedule who finishes internal medicine in June and starts as an attending in July is 40 percent vested, and leaves 60 percent of the hospital's contributions behind. Not a penalty, and nobody did anything wrong. It is what the schedule always said.
Cliff vesting is the sharper edge, because three years of service and three years of residency land close enough that a few weeks decide the outcome. One thing works in your favor: the clock usually runs from your hire date, not from the day the match started or the day you first enrolled.
Two complications. Plans run by state universities, public hospitals, and church-affiliated systems can sit outside those federal minimums, so the schedule may run longer than anything above. And fellowship usually restarts the clock, because the counter belongs to the employer rather than to you.
None of this argues against contributing. Your own contributions are never forfeited, and a partial match is still money you did not have.
So ask your benefits office two questions: which schedule the plan uses, and what percentage of the match you will actually have on your last day. Intern year is a far better time to learn that number than the spring you spend packing.