Part B Late Enrollment Penalty: How It Works and How to Avoid It
Part B Late Enrollment Penalty: How It Works and How to Avoid It
The Medicare Part B late enrollment penalty is one of the most expensive mistakes in the Medicare system — and it lasts for the rest of your parent's life. For every 12-month period your parent could have had Part B but didn't sign up, their monthly premium increases by 10%. That surcharge never goes away.
A parent who delays Part B enrollment by three years pays 30% more every month, permanently. On the 2026 standard Part B premium of $202.90/month, that's an extra $60.87/month — about $730 per year — for life.
How the Penalty Is Calculated
The penalty equals 10% of the current standard Part B premium for each full 12-month period the person was eligible but not enrolled.
Example: Your parent turned 65 in January 2023 and had no employer coverage. They didn't enroll in Part B until the General Enrollment Period in January 2026 — a three-year delay. Their penalty: 30% of the standard premium, added to every monthly bill indefinitely.
The penalty is recalculated each year as the standard premium changes. When the standard Part B premium goes up, the penalty amount goes up too.
Who's at Risk
The penalty applies when someone is eligible for Part B but doesn't enroll during their Initial Enrollment Period (IEP) — the seven-month window around their 65th birthday — and doesn't have qualifying employer coverage that would give them a Special Enrollment Period later.
Parents who are most at risk:
- Those who retired before 65 and had COBRA or marketplace coverage (neither counts as "creditable" to waive the penalty)
- Those who assumed they were covered through a spouse's retiree plan (retiree plans don't trigger a Special Enrollment Period)
- Those who were confused by the difference between Part A and Part B enrollment (you can have Part A without Part B)
- Those who live abroad and didn't realize they needed to enroll while away
When the Penalty Doesn't Apply
Your parent avoids the penalty if they had creditable employer coverage — meaning they or their spouse were actively working and covered by an employer group health plan (with 20+ employees) during the period they delayed enrollment.
When that employment or coverage ends, your parent gets a Special Enrollment Period: eight months to sign up for Part B without penalty. The eight-month clock starts the month after employment ends or the month after group coverage ends, whichever comes first.
Key distinction: COBRA, retiree health plans, marketplace plans, VA coverage, and TRICARE for Life do not qualify as creditable employer coverage for Part B purposes. Only active employment with active group coverage counts.
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How to Fix It (or Reduce the Damage)
If your parent is within the Special Enrollment Period: Enroll immediately. Call Social Security at 1-800-772-1213 or visit a local office. You'll need proof of prior employer coverage (a letter from the employer or insurer stating dates of coverage).
If the General Enrollment Period is the only option: Enrollment runs January 1 through March 31 each year, with coverage starting July 1. The penalty will apply, but enrolling now stops it from growing.
If the penalty is based on incorrect information: File Form CMS-L564 (Request for Employment Information) along with a letter from the employer confirming dates of active employment and group coverage. If Social Security applied the penalty in error, it can be removed.
IRMAA reconsideration: If your parent's penalty is compounded by Income-Related Monthly Adjustment Amounts (IRMAA) surcharges due to outdated income data, file Form SSA-44 to request a reconsideration based on a qualifying life-changing event.
Part B vs. Part D Penalties
Part D also has a late enrollment penalty, but it works differently. The Part D penalty is 1% of the national base beneficiary premium per month of delay (roughly $0.35/month per uncovered month in 2026). It's less severe than Part B's 10%-per-year hit, but it's also permanent.
Both penalties are avoidable with timely enrollment or qualifying prior coverage. Neither can be appealed away after the fact unless the delay was caused by incorrect information from Medicare or the employer.
Don't Let a Missed Deadline Compound
Late enrollment penalties are permanent — the earlier you catch them, the less damage they do. The Caregiver's Guide to Managing a Parent's Medicare includes an enrollment timeline, penalty calculator, and the exact forms needed to claim a Special Enrollment Period or correct an erroneously applied penalty.
Get Your Free A Caregiver's Guide to Managing a Parent's Medicare — Quick-Start Checklist
Download the A Caregiver's Guide to Managing a Parent's Medicare — Quick-Start Checklist — a printable guide with checklists, scripts, and action plans you can start using today.