Medicare Mistakes That Cost You Money—and How to Avoid Them

Medicare gives you choices — and choices, while valuable, also come with room for error. Every year, well-meaning beneficiaries make small missteps that end up costing them real money, delayed care, or unnecessary stress. The good news is that almost all of these Medicare mistakes are avoidable once you know what to look for.

Here are 5 of the most common Medicare mistakes we see, and how you can steer clear of them.

Mistake #1: Missing Deadlines

Medicare runs on a strict calendar — Initial Enrollment Period, General Enrollment Period, Annual Enrollment (October 15–December 7), and Medicare Advantage Open Enrollment (January 1–March 31), to name a few. Missing one of these windows can mean:

Late enrollment penalties that follow you for life
Gaps in coverage
Being locked into a plan that no longer fits your needs for another year

How to avoid it: Mark key dates on your calendar the moment they’re announced each year, and set reminders 30 and 7 days out.

Learn more about the enrollment periods at Medicare.gov.

Mistake #2: Choosing a Plan Based Only on the Premium

A low monthly premium can be tempting, but it doesn’t tell the whole story. Plans with lower premiums sometimes come with:

Higher deductibles or copays
Narrower provider networks
Limited or no coverage for the specific prescriptions you take

How to avoid it: Look at total estimated annual cost — premium plus expected out-of-pocket costs — not just the sticker price.

Mistake #3: Ignoring Prescription Drug Coverage

It’s easy to assume all Part D or Medicare Advantage plans cover medications the same way — they don’t. Formularies (the list of covered drugs) vary widely between plans, and a medication that was covered last year may be moved to a different pricing tier — or dropped altogether.

How to avoid it: Check your plan’s formulary every single year, even if you’re happy with your current coverage. Don’t assume nothing has changed.

Mistake #4: Not Reviewing Your Medicare Plan Annually

This might be the single most common — and most costly — mistake. Many people enroll in a plan once and never revisit it, assuming their coverage will simply “roll over” the same way each year. But plans change their costs, networks, and covered drugs annually, sometimes significantly.

How to avoid it: Set aside time every October to compare your current plan against other available options in your area, even if you don’t think you’ll switch.

Mistake #5: Assuming Original Medicare Covers Everything

It’s one of the most common surprises we hear about: someone needs a routine dental cleaning, a hearing aid, or a new pair of glasses — and discovers that Original Medicare (Parts A and B) doesn’t cover most dental, vision, or hearing services, or long-term custodial care.

How to avoid it: In previous years, we often recommended Medicare Advantage Plans for clients seeking added benefits. However, these extra benefits have become more limited recently. As a result, we now encourage clients to consider supplemental policies to help fill these gaps in coverage. Many of our clients are now adding dental, hospital, and cancer plans for extra protection.

Don’t wait until you need a service only to discover it isn’t covered.

A Simple Rule of Thumb

If you take one thing away from this post, let it be this: Medicare is not a “set it and forget it” benefit. A few minutes of review each year can prevent hundreds — sometimes thousands — of dollars in avoidable costs.

Medicare Mistakes That Cost You Money—and How to Avoid Them