Your first Medicare bill covers three months because Medicare Part B (medical insurance) charges are calculated on a quarterly basis, not monthly

When you turn 65 and enroll in Medicare Part B, your first bill arrives for January, February, and March combined — even if you enrolled in February or March. This happens because Medicare bills in three-month blocks called quarters, and you are charged for the entire quarter once you are enrolled in it. The bill you receive will show the premium amount multiplied by three months, or sometimes broken down by month.

This is different from how many other insurance plans work, and it catches many people off guard. The good news is that once you understand the pattern, your bills become predictable. After that first three-month bill, you will receive regular monthly bills or have premiums deducted from your Social Security check.

Key Takeaways

  • Medicare Part B bills arrive in three-month quarters, so your first bill covers three months of premiums even if you enrolled partway through a quarter.
  • The standard Part B premium for 2024 is $174.70 per month, but yours may be higher if your income is above certain thresholds.
  • You can pay your first bill by check, online through Medicare.gov, or by phone, and you have until the due date shown on your bill.
  • If you enrolled late in Part B without a valid reason, you may owe a permanent penalty added to your monthly premium for as long as you have Medicare.
  • Starting in the second quarter after enrollment, you can choose to have your Part B premium deducted directly from your Social Security payment.

How Medicare's Three-Month Billing Cycle Works

Medicare divides the year into four quarters: January through March, April through June, July through September, and October through December. When you enroll in Part B at any point during a quarter, you are responsible for the entire quarter's premium. If you enroll on March 15, you still owe for all of January, February, and March.

This system exists because Medicare's billing infrastructure processes claims and premiums in three-month blocks rather than individual months. The Centers for Medicare & Medicaid Services (CMS) sends out quarterly bills to millions of beneficiaries, and the system is built around that schedule. Your first bill will itemize the three months separately so you can see the breakdown, but the total due is for the full quarter.

After your first quarter, the pattern becomes regular. You will receive a bill each month (or have the amount deducted from Social Security), and each bill will cover only that single month's premium going forward.

What Your First Bill Should Show

Your first Medicare bill arrives as a document called a Medicare Summary Notice or sometimes labeled as an initial premium bill. It will show your name, Medicare number, and the three months of coverage. The bill lists the monthly premium amount and multiplies it by three, then shows the total due.

The bill also includes a due date — usually about 30 days from when it was mailed. Pay close attention to this date. If you miss it, your Part B coverage can be suspended, and you will have to contact Medicare to restart it. The bill will show a mailing address for payment by check, a phone number to pay by phone, and a website (Medicare.gov) where you can pay online.

Keep this first bill for your records. It serves as proof of your enrollment date and the premium amount you were charged. You will need it if you ever dispute a charge or if you need to show proof of coverage to a provider.

Income-Related Premiums and Why Your Bill Might Be Higher

The standard Part B premium changes each year. For 2024, the base premium is $174.70 per month, which means your first bill would be approximately $524.10 for three months. However, if your income is above certain thresholds, you will pay a higher amount called an Income-Related Monthly Adjustment Amount (IRMAA).

Medicare uses your tax return from two years prior to calculate IRMAA. If you had a high income in that year — for example, if you sold a house or received a large inheritance — your Part B premium could be significantly higher. The income thresholds vary by filing status (single, married filing jointly, married filing separately). Your first bill will show if an IRMAA applies to you, and it will break down the base premium and the adjustment separately.

If your income has dropped since that tax return was filed — for example, because you retired or your spouse passed away — you can request a Life-Changing Event review from Medicare. This allows you to use a more recent tax return to recalculate your IRMAA. Contact Medicare at 1-800-MEDICARE to request this review.

Late Enrollment Penalties on Your First Bill

If you delayed enrolling in Part B beyond your initial enrollment period and did not have a valid reason (called a may have access to event), your first bill may include a permanent penalty. This penalty is calculated as 10 percent of the base Part B premium for each full 12-month period you went without coverage. The penalty is added to your monthly premium for as long as you have Medicare — it does not go away.

For example, if you were may be able to access for Part B at age 65 but did not enroll until age 68, you owe a penalty for three years of delayed enrollment. That penalty is added to every single monthly bill you receive from that point forward. This is why it is important to enroll during your initial enrollment period, which begins three months before the month you turn 65 and ends three months after.

If you believe you had a valid reason for late enrollment — such as group health coverage through an employer, or a may have access to life event — you can appeal the penalty. Contact Medicare or your Social Security office to discuss your situation and provide documentation of your reason for the delay.

How to Pay Your First Bill

You have three main ways to pay your first Medicare bill. You can mail a check to the address shown on the bill, call 1-800-MEDICARE to pay by phone with a debit or credit card, or visit Medicare.gov and pay online. Online payment is usually the fastest and gives you when ready confirmation.

Do not wait until the due date to pay. If your payment arrives after the due date, your Part B coverage can be terminated. If this happens, you will need to contact Medicare to reinstate your coverage, and there may be a gap in your benefits. Pay as soon as you receive the bill.

Starting with your second quarter of enrollment, you can set up automatic deductions from your Social Security check. This means you will not receive a separate bill — the premium is straightforward deducted before your Social Security payment is deposited. Many people find this easier than managing separate bills. You can request this through Medicare.gov, by phone, or through your local Social Security office.

What Happens After Your First Three-Month Bill

After you pay your first bill, your coverage is active for those three months. In the following quarter, you will receive a new bill for the next three months. This pattern continues four times per year. Some people receive bills in the mail; others have premiums deducted from Social Security. The method depends on how you set up your account and whether you requested automatic deductions.

Your premium amount may change each year. Medicare announces the new Part B premium in the fall, and it takes effect January 1. You will be notified of any change before it happens. If you have an IRMAA, your premium may also change if your income changes or if you have a may have access to life event that affects your income calculation.

Keep track of your bills and payments. If you notice a charge that seems wrong — for example, if you are billed for a month after you switched to a different plan — contact Medicare right away. Errors can usually be corrected, but you need to report them promptly.

Frequently Asked Questions

Can I get my first bill broken into monthly payments instead of three months at once?

No. Medicare bills in quarterly blocks, and you owe the full three-month amount by the due date. However, once your coverage is active, you can request automatic monthly deductions from your Social Security check starting in the second quarter. This spreads the cost across months, even though you are technically paying the quarterly amount in pieces.

What if I enrolled in Part B but did not receive a bill?

Check your mail carefully — bills sometimes arrive in plain envelopes. If you enrolled online or by phone, confirm that Medicare has your correct mailing address. You can also log into your Medicare.gov account to view your bill online. If you still cannot find it, call 1-800-MEDICARE and ask them to mail a replacement or read the amount to you over the phone.

Do I owe the three-month bill if I die before the due date?

Your estate may be responsible for the bill through the due date. Contact Medicare as soon as possible after a death to report it. Medicare can sometimes adjust the bill to cover only the months the person was alive, but you need to notify them quickly. The person handling the estate should call 1-800-MEDICARE with the Medicare number and date of death.

Why does my first bill show a different amount than what I expected?

The most common reason is an IRMAA based on your income from two years ago. Your bill should break down the base premium and any adjustment separately. If the amount still does not match what you calculated, check whether a late enrollment penalty was added. You can also call 1-800-MEDICARE to ask them to explain each line on your bill.

Can I defer paying my first bill and start paying later?

No. Your Part B coverage begins on the first day of the month you enroll, and you owe the premium for that entire quarter. If you do not pay by the due date, your coverage will be terminated. You would then have to go through the enrollment process again and potentially face a late enrollment penalty. It is important to pay on time to keep your coverage active.