Whether you’re among the 53.5% of Americans who get their health insurance through work, the 20.1% enrolled in Medicare, or the 10.5% purchasing ACA coverage, mid-October or early November typically marks the start of the open enrollment period for next year’s insurance coverage.

Life would be easier if your health insurance coverage stayed the same if you liked it or adapted to your life automatically if you didn’t. Unfortunately, we mere mortals have to make decisions about our upcoming healthcare plan each year, in part because employers and other providers make regular changes to their insurance offerings—in addition to any legal changes that might affect federal benefits and ACA coverage.

The good news is that employers, Medicare providers, and the ACA marketplace typically time their open enrollment period to coincide, giving you November to make decisions about next year’s benefits.

But just because you know when to expect open enrollment season—who can miss all the open enrollment carols on the radio?—doesn’t mean you’re prepared for the important decisions you need to make. In fact, there are several common mistakes that could cost you big bucks in 2027 if you don’t know how to avoid them.

Here’s what you need to know about the most common open enrollment pitfalls.

The pitfall: missing a deadline

We all know how fast the fourth quarter tends to go. One minute you’re passing out candy to adorable Spidermen/Gwens and the next you’re eating Christmas cookies while making resolutions for 2027. The open enrollment deadline can get lost in the holiday shuffle.

For reference, these are the important deadlines for enrolling in a health insurance program during open enrollment:

• ACA Marketplace has two enrollment deadlines:
  • December 15, 2026 for coverage beginning January 1, 2027
  • January 15, 2027 for coverage beginning February 1, 2027
• Medicare: Enroll by December 7, 2026; coverage changes take effect January 1, 2027
• Employer-sponsored health insurance coverage: Your deadline will vary depending on your employer. Your HR department will have the necessary information.

There are two possible problems you may face after missing an open enrollment deadline:

1. You might have to go without insurance. If you miss the ACA open enrollment period, you can’t get insurance through the health insurance marketplace this year—unless you qualify for a special enrollment period. To qualify, you’d need to have gotten married or divorced, had a baby, moved, or lost your previous healthcare coverage.
2. You might be reenrolled in the same plan. Medicare beneficiaries who miss the open enrollment deadline are typically reenrolled in the same plan if it’s still offered. But it may not be the best option for your needs.

Workers with employer-sponsored insurance plans may still be able to enroll after missing a deadline, depending on how draconian the HR department is—but it’s not a good idea to count on it.

The pitfall: procrastination

As busy as this time of year can be, it’s rare that we miss an open enrollment deadline because it slips our minds. Instead, it’s much more likely that we procrastinate until the last minute. Humans tend to put off decision-making that feels overwhelming, confusing, or deeply boring—which is precisely the kind of choices you need to make during open enrollment.

Luckily, we know how to beat procrastination. If you know you have open enrollment decisions to make but have been putting them off, follow these steps to keep from procrastinating yourself sick:

1. Make it an appointment on your calendar. Set a specific time to deal with open enrollment paperwork. Schedule it in your calendar the same way you would a work meeting or doctor’s appointment.
2. Gather necessary information beforehand. After you make your “open enrollment appointment” on your calendar, generate a list of the things you think you’ll need to make decisions. Start gathering this information a little at a time. Some of the data you might need includes the names, birthdates, and Social Security numbers of every member of your household, pay stubs or tax returns to show your household income, how much you paid out of pocket in 2026, and your preferred healthcare providers and medications.
3. Spend no more than an hour on open enrollment. The reason we avoid tasks like open enrollment is that our brains convince us they’ll take forever. So give yourself permission to work for only 60 minutes. Stop at the end of the hour, even if you’re not completely done. Just schedule the next appointment before you quit for the day.
4. Don’t let perfectionism thwart your decisions: Part of what makes open enrollment nerve-racking is the fact that it’s impossible to know ahead of time if you’ve made the best decisions for next year’s healthcare needs. Trying to find the perfect plan option that will maximize your healthcare coverage while minimizing your out-of-pocket costs can drive you nuts, since a year of robust health may follow a year of multiple ER visits. Instead of aiming for a perfect plan, base your decision on what’s probable for 2027.

The pitfall: making assumptions

We often try to reduce the complexity of tough decisions by making assumptions. Unfortunat