Is Medicare Really Your Primary Payer? The Intake Question That Decides Whether a Clean Claim Gets Paid.
Your documentation can be perfect and the claim can still bounce, because someone else was supposed to pay first. Medicare Secondary Payer rules are an intake problem, not a billing problem.
Check this week:Pull your last 20 Medicare denials and look for CARC 22 ("this care may be covered by another payer per coordination of benefits"). If you find even a few, the fix isn't in billing. It's in how you ask about insurance on day one.
The denial nobody saw coming
Picture a Tuesday afternoon. A respiratory supplier delivers a portable oxygen setup to a 67-year-old who still works part-time at a school district. The order is signed. The qualifying test is on file. Proof of delivery is clean. The claim goes out to Medicare and comes back with a denial that has nothing to do with any of that: other coverage should have been billed first.
Nobody on the team did anything careless. The intake form had a field for "insurance," the patient said "Medicare," and that was that. Nobody asked the follow-up. The employer plan was sitting right there the whole time.
"The most expensive insurance question is the one you didn't ask because the patient already handed you a Medicare card."
Why Medicare isn't always first in line
Medicare is the primary payer for most beneficiaries, but not all of them. Under the Medicare Secondary Payer (MSP) rules, other coverage can pay first, and Medicare picks up behind it. The common situations a DME supplier runs into are fairly consistent.
A patient who is 65 or older and still covered by an employer group health plan, through their own job or a spouse's, may have that plan pay first when the employer has 20 or more employees. A patient under 65 who is on Medicare because of a disability may have a large group health plan pay first when the employer has 100 or more employees. Patients with end-stage renal disease generally have a 30-month coordination period during which a group health plan is primary. And when an item relates to an accident, injury or workers' compensation claim, liability insurance, no-fault insurance or workers' comp can be primary for related care.
Those are rules of thumb, and the details have exceptions. That's exactly why they can't live in one person's head. The point isn't to turn your intake coordinator into an MSP lawyer. It's to make sure the right questions get asked and the answers get recorded.
Where the gap turns into lost revenue
Here's the part that stings. A coordination-of-benefits problem usually surfaces weeks after delivery, when the equipment is already in the patient's home and the claim clock is already running. By then you're correcting payer order, rebilling, and chasing a second insurer who has its own rules and its own filing deadlines.
| What intake missed | How it shows up later | Downstream cost | Risk level |
|---|---|---|---|
| Employer group coverage never asked about | Medicare denies as "other payer should pay first" | Rebilling, delayed cash, possible timely-filing exposure with the real primary | High |
| Accident or injury link not screened | Medicare pays, then recovers the money later | Takebacks and reconciliation work on claims you thought were closed | High |
| Other card captured but never linked to the chart | Billing can't find it when the denial arrives | Hours of searching, a call to the patient, a stale answer | Moderate |
| Payer order assumed, not documented | Two staff members bill in two different orders | Inconsistent claims and no defensible record in a review | Moderate |
| Coverage never re-checked on recurring supplies | A patient retires or changes jobs; billing continues on old assumptions | Months of claims sent to the wrong payer first | High |
Notice what's missing from that table: clinical judgment. None of these are about whether the patient needs the equipment. They're about paperwork order, and paperwork order is the thing automation is good at.
Why eligibility checks alone don't catch it
A real-time eligibility check tells you whether Medicare coverage is active. That's useful. But a check like that is only as good as what's on file with the payer, and records of other coverage aren't always current. The patient who started an employer plan last month, or the one hurt in a fall that's now in litigation, may look perfectly clean on the screen.
So the safety net isn't a single tool. It's a short, consistent conversation with the patient and the referral source, recorded in a way billing can find later. The referral packet itself is often where the first clue lives: a face sheet listing a second insurer, a hospital discharge note mentioning an injury, a card photographed on page 9 of a fax.
"A claim sent to the wrong payer first isn't a billing mistake. It's an intake mistake that billing gets blamed for."
What good looks like
Suppliers who handle this well tend to do three unglamorous things. They ask the same MSP-style questions of every patient, in the same order, using the same script. They store the answers somewhere billing will actually look. And they revisit the answers on a schedule instead of trusting them forever.
A quick way to size the problem
Take your last month of Medicare denials and sort them by reason. Count how many trace back to other coverage. Then check how many of those patients had a second insurer visible somewhere in their original referral packet. If the answer is "most of them," the information was in the building. It just never reached the claim.
A pre-delivery checklist for payer order
Run this against your intake process before the next delivery goes out. Anything you can't tick is a place where a good claim can still get denied.
What to do this week
1. Write one script
A short list of insurance questions, the same for every patient. Put it where intake staff will see it, not in a binder.
2. Audit ten charts
Look for a second insurer in the referral packet that never made it into the patient record. Count how often it happens.
3. Decide who owns payer order
One named person, one place to record it. Shared ownership usually means nobody's.
Most suppliers will never lose a claim because of a clinical mistake. A lot of them lose claims because the right insurer wasn't asked first. That's fixable, and it's fixable before the equipment leaves the warehouse.
Catch payer-order problems before they become denials
DocuFindr reads inbound referral packets, surfaces insurance cards and face sheets, flags other coverage at intake, and keeps the payer-order record attached to the order, so billing sends the claim to the right place the first time. Bring a handful of real charts and we'll show you what we find.