Late Enrollment Penalty Checker Tool

Key takeaway: Late enrollment penalties for both Part B and Part D are permanent — they never expire, they never get forgiven, and they can easily cost you thousands of extra dollars over a retirement lifetime.

What this helps you decide

• The exact monthly dollar amount you'll owe in penalties based on how many months or years you delayed
• Whether the combined cost of both a Part B and Part D penalty significantly changes your retirement health budget
• How urgently you need to act — even a few more months of delay adds more permanent penalty cost
• Whether enrolling now (even late) actually saves you money compared to waiting for the next enrollment window

Who this is for

• Someone who missed their Initial Enrollment Period and wants to know what they'll owe before they enroll through the General Enrollment Period
• A person who had employer coverage that ended and didn't realize their Special Enrollment Period clock had started
• Anyone who went without Part D drug coverage for a stretch and needs to know how much that gap is going to cost going forward
• A couple trying to understand the combined financial impact of both penalties when one spouse delayed enrollment

Example results

Example 1 — Delayed Part B by 2 years (24 months, or 2 full 12-month periods). The Part B penalty is 10% per full 12-month period without coverage. Two full periods equals a 20% permanent penalty. Applied to the 2026 Part B premium of $202.90 per month: 20% of $202.90 is $40.58. Your Part B premium becomes $243.48 per month instead of $202.90. Over 12 months, that's an extra $486.96 per year. Over 20 years of retirement, that's $9,739.20 in extra premiums — and that calculation assumes premiums never increase, which they will. The real lifetime cost is likely higher.

Example 2 — Delayed Part D by 14 months. The Part D penalty is 1% of the national base premium per month without creditable coverage. In 2026, the national base premium is $38.99. So: 1% of $38.99 equals $0.3899, multiplied by 14 months equals $5.46 per month added permanently to your Part D premium. Your drug plan will cost at least $5.46 more every month, every year, for as long as you have Medicare. That's $65.52 per year in extra costs, added on top of whatever your plan's standard premium is.

Example 3 — Both penalties combined: 2-year Part B delay and 14-month Part D gap. Adding the two penalties from the examples above: $40.58 (Part B penalty) plus $5.46 (Part D penalty) equals $46.04 per month in extra premiums. Over one year, that's $552.48. Over 15 years of a typical retirement, that's $8,287.20 in extra costs purely from missing enrollment windows. This is the scenario that catches people the hardest — they delayed both, didn't realize both had separate penalties, and end up with a compounding monthly surcharge that follows them the rest of their lives.

Sample scenarios

What to do next

• Calculate your Part B penalty first: count the number of full 12-month periods you were without Part B and had no qualifying coverage. Multiply that number by 10%, then by $202.90.
• Calculate your Part D penalty separately: count the months without creditable drug coverage, multiply by 1%, then multiply by $38.99.
• Even if you'll owe penalties, enroll as soon as your next available window opens — every additional month of delay makes the penalty larger and the break-even on enrolling worse.
• If you think you had creditable coverage during the gap period (like VA drug benefits or an employer plan), gather documentation before enrolling — it could reduce or eliminate your Part D penalty.

Key facts

• The Part B late enrollment penalty is 10% of the current monthly Part B premium for each full 12-month period without coverage. In 2026, the base premium is $202.90/month, making each 12-month delay period worth $20.29/month in permanent additional cost.
• The Part D late enrollment penalty is 1% of the national base beneficiary premium ($38.99 in 2026) multiplied by the number of full months without creditable prescription drug coverage. It is rounded to the nearest $0.10 and added to your monthly Part D premium permanently.
• Both penalties are recalculated against the current premium each year as premiums rise, so the dollar amount of your penalty can increase over time even though the percentage is set at the time of enrollment.

Related decisions

• Part B penalty calculator — Get a detailed breakdown of the Part B penalty by year of delay.
• Part D penalty calculator — See exactly how much your drug coverage gap will cost month by month.
• Initial Enrollment Period calculator — Check whether you're still within your original enrollment window.
• Special Enrollment Period guide — Find out if a life event gives you a penalty-free enrollment window.