What happens if you do nothing this fall: the defaults in Medicare and the Marketplace

Fall enrollment coverage tends to be written for the person who wants to switch. Most people don't. The more common question is quieter: what happens if I simply leave it alone?

Both systems have an answer, and in both the answer is roughly the same shape. You generally stay covered. What you keep is next year's version of your plan, which is not always the same product you signed up for.

Medicare

The sequence starts in September, when your plan sends the Annual Notice of Change describing what will be different in January — we covered how to read it in the September envelope. Then the Open Enrollment Period runs October 15 to December 7, with changes taking effect January 1 as long as the plan has the request by December 7. Medicare's enrollment period table lists each window and when coverage starts under it.

If you do nothing in that window, you generally continue in your plan as it exists next year — new premium, new cost sharing, new drug list, new network. The plan continues; its terms are the ones described in the notice you received in September.

There is one case where the default doesn't hold: a plan can leave the Medicare program. Medicare's guide to coverage mailings lists the notices that arrive when that happens — a plan non-renewal notice from the plan in October, a reminder from Medicare in November. Those letters ask for a decision, and they are the ones not to file unopened.

There is also a limited second chance. If you are in a Medicare Advantage plan, the Medicare Advantage Open Enrollment Period runs January 1 to March 31 and allows one switch to another Medicare Advantage plan or a return to Original Medicare. It is narrower than the fall window, and it is not a substitute for it.

The Marketplace

The marketplace default is more active. Open Enrollment runs November 1 to January 15. By November 1, HealthCare.gov says you should get two letters — one from your insurance company and one from the Marketplace — telling you whether your current plan is available next year and which plan you would be automatically re-enrolled in if you don't act.

If you take no action by December 15, you may be automatically re-enrolled for coverage starting January 1. HealthCare.gov also notes plainly that in some cases you won't be automatically re-enrolled — which is why the letters matter even when the plan is fine.

The piece that doesn't happen on its own is the financial one. Marketplace savings are based on the income you expect for the year you're applying for, not on past years. If your application still carries last year's estimate, HealthCare.gov's own framing covers both directions: you could qualify for more savings than you're getting, or for less and have to pay back the difference at tax time. Updating the application is a separate action from keeping the plan. We wrote about the two different income clocks in one income number, two systems.

So what does “doing nothing” actually cost

Usually not coverage. What it costs is information — finding out in March what changed in January. The three things most worth checking against next year's terms are the ones that tend to move: your prescriptions, your doctors, and, in the Marketplace, the income estimate the savings are calculated from.

Nothing is due yet

It's late August. No window is open and nothing is due. The only thing this season asks is that the fall mail gets opened rather than stacked — the September notice from a Medicare plan, and the two November letters if you have marketplace coverage. If you'd like the short version of what to have ready, we listed it in four things to write down before fall, and the full sequence of dates is in the fall coverage calendar.

And if you'd rather have someone read the notices with you when they arrive and tell you whether anything on your list moved, that's a free, no-pressure conversation with a licensed agent — including the conversation that ends with “nothing to change this year.”