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Why Does Medicare Deny CO-22 for Patients Who Are Still Working Past 65?

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Medicare denies CO-22 for patients working past 65 because of the Medicare Secondary Payer rules: when a patient age 65 or older is covered by a group health plan through their own or a spouse’s current employment at an employer with 20 or more employees, that group plan is primary and Medicare pays secondary. When your intake never runs the MSP questionnaire, the practice does not know the employer plan comes first, so the claim goes to Medicare, and Medicare returns CO-22 telling you to bill the other payer. It is almost never a coding problem; it is a coordination-of-benefits problem that started at registration. The fix has four moves: run the MSP questionnaire at intake and again each year for every Medicare patient, identify the primary payer before the claim drops, bill the employer plan first, then submit to Medicare secondary with the primary remittance attached. We run those moves inside the systems you already use, so a working-aged patient stops turning into a reworked claim. The table of contents maps the whole method; the moves after it are the detail.

How to Stop Working-Aged Claims From Denying CO-22
Key Pain Points and Discussions by Providers
Why This Keeps Happening
The Solution
How We Permanently Fix the Process
The Whole Thing in Four Sentences
Frequently Asked Questions
Where the Claims on This Page Come From

How to Stop Working-Aged Claims From Denying CO-22

The goal is simple: every Medicare patient screened for a primary payer before the claim drops, so the working-aged ones bill in the right order the first time. Here is what does that, move by move.

1. Run the MSP Questionnaire at Intake, Every Medicare Patient

The denial starts at registration, so that is where you stop it. Medicare expects providers to gather coordination-of-benefits data using the Medicare Secondary Payer questionnaire, and it is the front-line tool for catching a working-aged patient before you bill. Ask every Medicare patient the questions that matter: are you or your spouse currently working, is the employer large, are you covered by a group health plan through that job. When the answer flags a working-aged situation, you have caught it before the claim exists rather than after Medicare bounces it.

2. Re-Screen Every Year, Because Employment Status Changes

A one-time screening at the first visit is not enough. A patient who retired last year and made Medicare primary may have gone back to work; a spouse’s coverage may have started or ended. Medicare’s own guidance treats MSP status as something to verify on an ongoing basis, so re-run the questionnaire at least annually for every Medicare patient on the panel. The working-aged situation you missed is usually the one where last year’s answer quietly stopped being true, and nobody asked again.

3. Identify the Primary Payer Before the Claim Drops

Once the questionnaire flags a group health plan through current employment at a large employer, treat that plan as primary. Capture the plan name, member ID, and payer ID at intake, verify the coverage is active, and note the coordination-of-benefits order in the account before anyone bills. The whole point is to know the billing order at the desk, not to discover it on a CO-22 remittance three weeks later when the visit is already old.

4. Bill the Group Plan Primary, Then Medicare Secondary

With the order known, the claim goes to the employer plan first. When that plan pays or denies, you submit to Medicare secondary with the primary remittance attached so Medicare can coordinate benefits and pay its portion. Done in the right order, the claim never generates a CO-22 in the first place, and the working-aged patient stops being the account that reworks itself every visit. For claims that already denied, the same rework rebills to the primary and then to Medicare secondary with proof of the original filing to protect timely filing.

5. Hand MSP Screening and Secondary Billing to a Dedicated Team

Practices that stop reworking working-aged denials do it by handing MSP screening and coordination of benefits to a dedicated team: remote specialists who run the questionnaire, verify the primary payer, bill in the right order, and rework the CO-22s that already landed, live in 1 to 2 weeks. The front desk stops guessing at coverage between check-ins, a trained backup covers every gap, and the working-aged patient stops being the denial nobody owns. Below is what it sounds like when nobody owns it yet, in providers’ own words.

Key Pain Points and Discussions by Providers

real reports from practice staff, lightly edited

“We bill Medicare for a patient who is clearly over 65 and it comes back CO-22 telling us there is another primary payer. Half the time nobody at the desk knew the patient was still working, because we never actually ask. It is a clean visit we now have to unwind.” – billing lead, primary care practice

“The MSP questionnaire is on our intake form, but it gets skipped when the waiting room is full. Then three weeks later I am the one reworking the denial, calling the patient to find out where they work and whether the spouse has a plan. That conversation should have happened at check-in.” – practice administrator, primary care group

“What kills us is the patients who retired, went back to work, and never told us. Last year Medicare was primary, this year the employer plan is, and our system still had it the old way. The first sign we get is a CO-22, and by then the visit is aging.” – office manager, family medicine practice

“We screen new patients once and never again. So the working-aged ones who change jobs or whose spouse picks up new coverage slip right through, and every one of those is a denial and a rebill in the wrong order.” – billing lead, multi-provider practice

“Reworking a CO-22 is not just resubmitting. I have to bill the employer plan, wait for that remittance, then send Medicare secondary with the paperwork attached. One skipped question at the front desk turns into a month of me chasing the right billing order.” – coder, primary care practice

Our Answer

Here is what we actually do. A dedicated remote specialist runs the Medicare Secondary Payer questionnaire for every Medicare patient at intake and again each year, so a working-aged patient with a group health plan through current employment is caught before the claim drops. They capture the primary payer, verify the coverage is active, and set the coordination-of-benefits order in the account, then bill the employer plan first and Medicare secondary with the primary remittance attached. For CO-22 denials that already landed, they rebill in the correct order with proof of the original filing to protect timely filing. Our specialists are credentialed professionals, overseas-trained physicians and US-licensed nurses and pharmacists, working inside your practice management and clearinghouse tools, with AI drafting the first pass and a human verifying every submission. This is our denial management support paired with an AI-first workflow, in one paragraph.

Why This Keeps Happening

If the visit was clean, why does Medicare keep denying it CO-22? Because the denial has nothing to do with the visit. Under the Medicare Secondary Payer rules, a patient age 65 or older who is covered by a group health plan through their own or a spouse’s current employment at an employer with 20 or more employees has that group plan as their primary payer, and Medicare pays secondary. CMS is explicit that providers are expected to gather this coordination-of-benefits information, and the MSP questionnaire is the tool built for it. When the question never gets asked, the practice bills Medicare in good faith, and Medicare returns the claim because it was never first in line.

The gap is almost always at the front desk, not the billing office. Intake is the one moment you can ask a patient directly whether they or their spouse are still working, at what size employer, and under what plan, and it is the moment most likely to get skipped when the schedule is full. So the working-aged status the practice needed to know never enters the account, and the claim routes to Medicare by default. Catching it at registration is exactly the kind of front-office accuracy an insurance eligibility verification workflow is built to protect, because the denial is decided before a single code is entered.

And the cost is not just one reworked claim. A CO-22 rework is not a resubmission; it is billing the employer plan primary, waiting on that remittance, and then filing Medicare secondary with the primary explanation of benefits attached, all while the visit ages toward a timely filing deadline. Multiply that across a Medicare-heavy panel where working-past-65 is increasingly common, and the quiet miss at intake becomes a standing pile of secondary rebills, delayed cash, and accounts that sometimes age out entirely before anyone untangles the billing order.

⚠️ The quiet one that hurts most: The quiet one that hurts most: the patient who used to be Medicare-primary and is not anymore. They retired, you correctly billed Medicare first, and then they went back to work at a large employer and never mentioned it. Your account still shows Medicare primary, so every claim keeps routing there and keeps coming back CO-22, one after another, until someone re-runs the questionnaire. A single stale answer at intake does not fail once; it fails on every visit until the year you finally ask again. Unless someone re-screens the panel on a schedule, the most persistent CO-22 denials are the ones where last year’s right answer quietly became this year’s wrong one.

Most groups have already tried the obvious fixes before they talk to anyone. Each one fails the same way: the work lands back on the practice. The pattern, in one table:

What you tried	What actually happened	Who ended up doing the work
Put the MSP questionnaire on the intake form	It gets skipped when the waiting room is full, so the working-aged status never reaches the claim	Whoever was at the check-in desk that day
Screened new patients once at their first visit	Patients who returned to work or whose spouse gained coverage slipped through and denied CO-22 anyway	A one-time form nobody revisited
Reworked each CO-22 as it landed	Turned a clean visit into a month of billing the employer plan, waiting, then filing Medicare secondary	The billing office, one denial at a time
Gave MSP screening to a dedicated remote specialist	Every Medicare patient screened at intake and yearly, primary payer set before the claim drops, denials reworked in order	Someone whose whole job it is

The Solution

So what does “someone whose whole job it is” look like on a working-aged Medicare patient? The specialist runs the MSP questionnaire at intake for every Medicare patient, not just new ones, and asks the questions that actually decide the billing order: current employment, employer size, spouse coverage, group health plan. When a patient flags as working-aged, they capture the employer plan as primary, verify it is active, and set the coordination-of-benefits order in the account before anyone bills. That front-office catch is exactly what dedicated insurance eligibility verification is built to do, before a clean visit ever becomes a CO-22.

Then comes the part the front desk rarely has time for: billing in the right order and reworking the ones that already denied. The specialist bills the group plan primary, waits on that remittance, and submits Medicare secondary with the primary explanation of benefits attached so Medicare can coordinate benefits correctly. For CO-22s already on the aging report, they rebill in the proper sequence with proof of the original filing so timely filing is protected. The accounts that used to sit and age get worked the same way every time, on a schedule.

Behind all of it, AI drafts the first pass and a credentialed human verifies. The workflow flags which Medicare patients are due for re-screening, drafts the coordination-of-benefits order, and queues the secondary claim; a person confirms the primary payer is right and owns the rework. Every security control that protects the patient and coverage data moving through that process is documented and auditable, and the whole approach is described on our HIPAA and security page, because moving eligibility and claim data through an outsourced workflow is only safe when the controls are real.

Who Actually Does This Work

Fair question: why would an outsourced team screen your Medicare patients better than your own front desk? Because coordination of benefits is their entire day, not the thing they squeeze between a full waiting room and a ringing phone. The people running your MSP screening and secondary billing are credentialed medical professionals: overseas-trained physicians, US-licensed nurses and pharmacists, and PharmDs, all trained in US registration, eligibility, and coordination-of-benefits workflows. They know what the MSP questionnaire is checking for, how the working-aged rule works, and how to bill Medicare secondary correctly, so a working-past-65 patient is caught at intake instead of discovered on a remittance.

We are not a call center. We are a clinical operations partner, a healthcare BPO built on dedicated virtual staff: 500+ credentialed professionals, 24/7 coverage, and the AI-first-pass plus human-verify workflow you just read about behind every one of them. A typical practice is live in 1 to 2 weeks, at up to 70% below the cost of hiring locally, and no one on our side goes out without a trained backup already inside your workflow, so MSP screening never lapses because the one person who handles it is on vacation.

And the security piece your compliance officer will ask about: we are audited to SOC 2 Type II with zero exceptions and certified for ISO/IEC 27001:2022, HIPAA, and GDPR, with zero breaches in eight years. Every workstation runs inside a secure enclave on US-based servers, with screen captures and downloads blocked by policy, so PHI never sits on someone’s home laptop. Every client account carries a $5M E&O and cyber liability policy and a BAA signed before any work starts; the full detail lives in our HIPAA and security posture.

Put the routine and the people together, and a specific list of things simply stops happening.

✓ What stops happening: What stops happening: the clean visit that comes back CO-22 because nobody asked whether the patient still works. The month-long rework of billing the employer plan, waiting, then filing Medicare secondary. The retired-then-rehired patient whose account still says Medicare primary and denies every single visit. The MSP questionnaire that gets skipped when the schedule is full. The secondary rebills piling up on the aging report while the visits creep toward timely filing.

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How We Permanently Fix the Process

A person alone is not the fix, and neither is a bot alone. The fix is a documented coordination-of-benefits workflow: which Medicare patients get screened, when they get re-screened, exactly which MSP questions decide the billing order, and how a working-aged claim gets billed primary then secondary. Before we take a single account for a new practice, we chart your Medicare panel and your CO-22 history so we can see where working-aged patients are actually slipping through, and we build the screening cadence against that, not against a generic checklist.

From there the workflow becomes a living playbook rather than a form nobody revisits. It records which questions to ask, how to read a working-aged answer, how to set the coordination-of-benefits order in your system, and the exact steps to bill the employer plan primary and Medicare secondary with the right attachments. It is written down, kept current, and owned by the team. When your specialist is out, a trained backup runs the same questionnaire and the same billing order, so a working-aged patient never slips because one person was away that week.

That is the difference between reworking this month’s CO-22s and fixing the process for good, and it is what a dedicated revenue cycle management partner actually buys you. A coordinator leaving used to mean the MSP screening quietly stopped and the working-aged denials came back. Under this model the screening keeps running, the playbook stays, the backup steps in, and a CO-22 stops being the denial that reworks itself every visit.

The Whole Thing in Four Sentences

Medicare denies CO-22 for patients working past 65 because the Medicare Secondary Payer rules make a group health plan primary when the patient or spouse is still working at an employer with 20 or more employees, and intake never ran the MSP questionnaire to catch it, so the claim routed to Medicare first. Skipping the questionnaire, screening only once, or reworking each denial as it lands all fail the same way. The fix is to run the MSP questionnaire at intake and every year, identify the primary payer before the claim drops, bill the group plan primary, and submit Medicare secondary with the primary remittance attached. A primary care group runs exactly this model with us today, names withheld, no patient data shown.

If you want to check us out before talking to anyone: our security posture is independently auditable, we are an MGMA 2026 Corporate Member, and 800+ providers run back office work with us.

Ready to stop reworking working-aged denials? Try us risk free: two weeks, your real Medicare panel and CO-22 queue, dedicated specialists running the MSP screening and billing in the right order, and if it does not earn the handoff, you walk away. From here down is the sales part, and it is short: here is exactly what it costs.

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One Flat Weekly Rate. 45 Hours of Coverage.

No hourly meters, no setup fees, no long-term contracts. Your dedicated team member covers your desk 45 hours every week, and a trained backup steps in at no charge whenever they are out.

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$399/ week

One dedicated remote specialist owning your MSP screening and CO-22 denial rework end to end, single-location primary care practice

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Frequently Asked Questions

Why does Medicare deny CO-22 for a patient who is clearly over 65?

Because age alone does not make Medicare primary. Under the Medicare Secondary Payer rules, a patient 65 or older who is covered by a group health plan through their own or a spouse’s current employment at an employer with 20 or more employees has that group plan as primary and Medicare as secondary. CO-22 is Medicare telling you the care may be covered by another payer per coordination of benefits, so the claim needed to go to the employer plan first.

What is the MSP questionnaire and who has to fill it out?

The Medicare Secondary Payer questionnaire is the set of questions a practice asks a Medicare patient to determine whether Medicare is primary or secondary. CMS expects providers to gather this coordination-of-benefits information, and the questionnaire is the tool built for it. It asks about current employment, employer size, spouse coverage, and other insurance, and the answers decide which payer to bill first. It should be run at intake and repeated on an ongoing basis, not filled out once and forgotten.

How often should we re-screen Medicare patients for secondary payer status?

At least once a year, and any time coverage might have changed. Employment status is not static: a patient who retired and made Medicare primary can go back to work, and a spouse’s coverage can start or stop. The most stubborn CO-22 denials come from accounts where last year’s answer was right and this year’s is wrong, and nobody asked again. Re-running the questionnaire annually across the panel catches those before they bill.

How do we correctly bill a working-aged claim so it does not deny?

Bill the group health plan primary first. When that plan pays or denies, submit to Medicare secondary with the primary remittance or explanation of benefits attached so Medicare can coordinate benefits and pay its portion. Done in that order, the claim does not generate a CO-22. For denials that already landed, rebill in the same sequence and keep proof of the original submission to protect the timely filing window.

How much does outsourced MSP screening and denial rework cost?

Staffingly charges a flat weekly rate per dedicated remote specialist, with lower per-person rates for teams of 5 or more and 10 or more, and a trained backup included. There is no percentage of your collections. The pricing section on this page shows how the flat rate compares with typical US market rates for this work.

Will AI be making coverage or billing decisions on our claims?

No. AI drafts the first pass, flagging which patients are due for re-screening, drafting the coordination-of-benefits order, and queuing the secondary claim, and a credentialed human verifies the primary payer and owns the rework. The judgment stays with people. Automation removes the repetitive assembly so the specialist spends their time on the accounts that need a human, not on retyping the same secondary-billing steps.

Do we have to change our practice management or clearinghouse system?

No. Our specialists work inside the registration, eligibility, and billing tools you already use, so there is no migration and no new platform for your staff to learn. They run the questionnaire, set the coordination-of-benefits order, and submit primary and secondary claims where your accounts already live, which is why a typical practice is live in 1 to 2 weeks rather than months.

How fast will we see fewer CO-22 denials?

Usually within the first few weeks. Once a dedicated specialist is running the MSP questionnaire at intake and re-screening the panel, the working-aged patients get caught before the claim drops, so the CO-22s stop generating at the source. The denials already on the aging report get reworked in the correct billing order in parallel, so the pile shrinks from both ends.

How does one flat weekly rate cover 45 hours every week?

Your dedicated specialist works a 9-hour day, Monday to Friday, which is 45 hours of coverage each week. The ninth hour is part of the flat weekly rate, not billed as overtime. Over a year that is 2,340 hours of coverage, against the standard US full-time work year of 2,080 hours (40 hours x 52 weeks, the same basis the U.S. Office of Personnel Management uses to compute hourly rates of pay). That is how $399 per week works out to $8.87 per hour.

Written By

Dan Nandan

Founder and CEO, Staffingly, Inc. · Piscataway, NJ

Dan Nandan has spent 25+ years in IT consulting and healthcare BPO, was among the first in the US to build an RPO/BPO delivery network in India, and has been featured in Computerworld. He runs the operations and the dedicated virtual teams behind the workflows on this page; the team-voice answers above come from the remote specialists who work them every day.

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Where the Claims on This Page Come From

Sources & References

Centers for Medicare and Medicaid Services, Medicare Secondary Payer Overview. Official CMS guidance on coordination of benefits, the working-aged provision, and when a group health plan is primary to Medicare. cms.gov
CMS Medicare Secondary Payer (MSP) Manual, Chapter 3. Detailed MSP provisions and the provider responsibility to gather coordination-of-benefits data, including the model MSP questionnaire. cms.gov
CMS Medicare Secondary Payer Fact Sheet (MLN006903). Provider-facing summary of MSP rules, the working-aged category, and correct primary-then-secondary billing order. cms.gov
MGMA Practice Operations and Revenue Cycle Resources. Benchmarks and guidance on front-office accuracy, eligibility, and coordination-of-benefits workflow for medical group practices. mgma.com
HFMA Revenue Cycle and Denials Management Resources. Guidance on coordination-of-benefits denials, secondary billing, and the revenue impact of misrouted claims. hfma.org