The Part B paperwork mistakes that hold up your coverage

Medicare enrolment is not hard. It is just unforgiving about small things, and the feedback loop is terrible, because a form that goes wrong in March does not announce itself until May.

I supervised a postal processing facility in Erie for nineteen years, so I have a particular sympathy for forms that fail because of something stupid rather than something substantive. Most of these do.

Two forms, not one

If you are signing up for Part B outside your initial enrolment window because you were covered by an employer plan, you need two forms and most people send one.

CMS-40B is your application. CMS-L564 is the employment verification, and your employer's human resources department has to complete part of it. Sending the 40B alone gets you a letter asking for the L564, and that round trip costs you weeks.

Start the L564 first, because it depends on somebody else. Companies get bought, HR moves offshore, and the person who can sign it may take a fortnight to locate. If the employer no longer exists, there is a procedure using pay stubs and tax records instead, and you want to discover that early rather than late.

The errors I see over and over

The name. Use the name exactly as it appears on your Social Security card. If you married and the card says one thing and your driving licence says another, the card wins. A mismatch stops the file dead and generates no explanation.

The remarks box on CMS-40B. If you are enrolling during a special enrolment period because your group coverage ended, write it there in plain words with the date the coverage ended. Leave it blank and the system has no idea why you are applying outside the normal window.

The employment dates on the L564. They must be the dates you were covered by the group plan, which are not always the dates you were employed. Coverage often continues to the end of the month after you finish. Get those wrong and they contradict what the employer reports.

Unsigned forms. It happens constantly. Check the signature and the date before it leaves your hands.

And do not send photocopies of identity documents where they ask for certified copies. It sounds like a distinction nobody enforces. They enforce it.

Proving you sent it

This is the part I care most about, for obvious reasons.

Send it in a way that produces a receipt. Certified mail with return receipt costs a few dollars and it is the only thing that settles an argument about whether a document arrived. If you upload through your ssa.gov account, save the confirmation screen as a file. Do not trust that the record will be there later.

Write the date you sent it on your own copy of the form. Keep the copy.

I know how mail works. The overwhelming majority of it arrives exactly as it should. But a small number of items do not, and when it is your health coverage in that small number, the fact that the system generally works is no comfort at all.

Following up

Give it three weeks, then check. You can look at the status in your ssa.gov account, or call.

If you call, ring the moment the lines open. Do not ring on a Monday and do not ring in the first days of a month. And be ready for the hold music, which I have opinions about that are not printable.

Have your Social Security number, the date you sent the forms, and the name of anyone you have already spoken to. Ask for a reference number for the call and write it down. Without one you are starting from nothing every time.

The deadline you cannot miss

A special enrolment period after employer coverage ends runs eight months. That sounds generous and it deceives people, because retiree coverage and COBRA do not count as active employer coverage for this purpose. The clock starts when the employment or the group coverage ends, whichever comes first, not when your COBRA runs out.

People on COBRA regularly believe they are still protected, use up the eight months, and end up with both a gap in coverage and a lifelong late enrolment penalty on the premium.

If you are in that situation, sort it now. Not after COBRA finishes.

The standard Part B premium for 2026 is $202.90 a month with a $283 annual deductible. Confirm the current figures at medicare.gov before you plan around them, because they move every year.