Working Past 65: Whether You Can Delay Medicare Turns on Your Employer’s Headcount

Updated August 1, 2026. Quick answer: whether you can safely delay Medicare while still working turns on a number that has nothing to do with you: whether your employer has 20 or more employees. At or above it, the group plan pays first and delaying is protected. Below it, Medicare is the primary payer whether or not you enrolled — and your group plan can pay as though Medicare had already covered its share, leaving you with the gap and a penalty clock running.

The threshold, and how the count is actually done

“This requirement applies if an employer has 20 or more full-time and/or part time employees for each working day in each of 20 or more calendar weeks in the current or preceding year. Self-employed individuals who participate in an employer plan are not counted as employees in determining if the 20 or more employees requirement applies.”

CMS Pub. 100-05, Medicare Secondary Payer Manual, ch. 1 § 20.1 (Working Aged)

Three details inside that sentence that decide real cases: part-time employees count; the test looks at the current or the preceding year, so a firm that shrank below 20 last year may still be above the line; and self-employed participants are not counted. A 19-employee practice where two partners are self-employed is not a 21-person employer for this purpose.

The decision, both branches

The under-20 branch is the dangerous one precisely because nothing goes wrong until a claim. You hold a card, premiums come out of your pay, and the arrangement looks identical to your colleagues’. The difference only surfaces when the plan processes a bill as secondary payer and the primary share — the share Medicare would have paid — is yours.

Two variants of the rule people apply to themselves wrongly

If Medicare entitlement is based on disability rather than age, the threshold is not 20 — it is a large group health plan of 100 or more. And where entitlement is based on end-stage renal disease, a group health plan of any size is primary during the coordination period. Reading the 20-employee rule across to either case gives the wrong answer in the expensive direction.

When the job ends

The Special Enrollment Period runs 8 months, and “Ends 8 months after the group health plan coverage or the employment ends, whichever happens first.” The two things that do not extend it are the two things people reach for: “COBRA isn’t considered group health plan coverage. Getting COBRA doesn’t change when this Special Enrollment Period ends.” Retiree coverage is treated the same way. If you are negotiating an exit package, the Medicare clock starts with the employment or the coverage ending — not with the severance running out.

The HSA question underneath this

For many people the real reason to delay is the HSA, and that is a legitimate reason: you can keep contributing only while you are not enrolled. But it sets up the trap on the way out, because Medicare backdates when you eventually do enrol — six months of contributions become excess retroactively unless you stop in time.

If the delay turns out not to have been protected, the Part B penalty and the Part D penalty price it. For the dates, your enrolment window. And if you are still earning at 65, your income two years back is already setting your premium.

Employer-size and payer-order rules from the CMS Medicare Secondary Payer manual ch. 1 and 42 CFR part 411; enrolment-period rules from medicare.gov. Read August 1, 2026. General information, not advice — and employer size is a question for your benefits administrator, in writing.