UpTrajectory Review

Kiplinger flags one of the most quietly expensive mistakes in retirement planning: the Medicare Part B enrollment penalty that hits people who keep working past 65 and assume their employer coverage protects them. The trap is mechanical. At 65 you become eligible for Medicare, but delaying Part B is only penalty-free if your employer's plan counts as primary coverage. That hinges on a single threshold the source barely gets to explain before the text cuts off: whether your employer has 20 or more employees. Below that line, Medicare becomes your primary payer whether you enroll or not, and your employer plan may start paying claims as if Medicare already covers its share.

For small-business owners and their employees, this is not an abstract edge case. It is the exact demographic this publication serves. Small employers often have plans that were never designed with Medicare coordination in mind, and HR departments at companies with fewer than 20 workers may not flag the issue because it rarely comes up. If you are the owner still on your own group plan at 66, or you employ someone in that situation, the penalty is permanent: Part B premiums rise 10 percent for every 12-month period you were eligible but not enrolled, and that surcharge follows you for life. On current premiums, that is real money compounded across a long retirement.

What is genuinely useful here is the framing: this is not a knowledge problem, it is an assumption problem. The people who get caught are the ones who did everything right, stayed insured, kept working, and never thought to ask whether their coverage still counted. We agree with the source that the 20-employee threshold is the critical and underappreciated detail. Where we push back slightly is the implication that larger-employer workers are entirely safe. Even they need to confirm their plan is creditable, coordinate timing with HR, and watch the special enrollment window, which lasts only eight months after employment or coverage ends.

The second-order effects reach beyond the individual. For small employers, an employee who delays Medicare enrollment and gets hit with a permanent penalty may blame the company for not warning them, creating a friction point that costs nothing to prevent. There is also a coverage-gap risk that is arguably worse than the penalty: if Medicare is your primary payer and you are not enrolled, your employer plan may deny claims it would otherwise cover, leaving you exposed to full medical bills at exactly the age when healthcare use spikes. That is a financial hole no premium surcharge compares to.

The action item is straightforward. If you or anyone on your payroll is 65 or older and still working, verify the employer headcount, confirm whether the plan is creditable for Part B purposes, and if the company is under 20 employees, enroll in Medicare during the initial enrollment window to avoid both the penalty and the coverage gap. Owners should also brief their HR or benefits administrator so the question gets raised proactively during open enrollment. The source is thin on the mechanics, but the warning is sound: this is one deadline that does not forgive.

Watch for further guidance from Kiplinger's Adviser Intel contributors on how the special enrollment period actually works in practice, and whether proposed legislation to simplify Medicare coordination for working seniors gains any traction. In the meantime, the eight-month special enrollment clock after retirement is the other trap: miss it, and the penalty applies even if you had perfect coverage your entire career. Mark the date, set the reminder, and treat Medicare enrollment with the same rigor you would any other business deadline.

“A Medicare enrollment trap springs most often on the very people who feel least worried about it: Those working past 65 with what they assume is perfectly good employer coverage.” — Kiplinger

Takeaway: If you or an employee is 65+ and still working at a company with fewer than 20 employees, enroll in Medicare Part B now to avoid a permanent premium penalty and potential coverage gaps.