A Clear Guide for Private Practices
Understanding Medicare enrollment status is essential for any medical practice—especially when it comes to clean claims, secondary insurance coordination, patient billing workflows, and overall revenue cycle efficiency.
Whether you’re a physician, practice manager, or billing team member, knowing the differences between Participating (PAR), Non-Participating (Non-PAR), and Opt-Out status is foundational to avoiding denials, preventing patient confusion, and protecting revenue.
This guide breaks down each Medicare status in clear, billing-focused terms and explains how each impacts:
- Medical billing
- Reimbursement
- Secondary insurance payments
- Patient collections
- Compliance
Participating Provider (PAR)
Definition
A participating provider is enrolled in Medicare and agrees to accept Medicare’s approved amount as full payment for all covered services. This includes agreeing to accept assignment on every claim.
How PAR Status Affects Medical Billing
- Medicare pays you directly at the full allowable rate
- Claims automatically crossover to secondary insurance (Medigap, retirement plans, etc.)
- Patient responsibility is limited to deductibles, copays, or coinsurance
- Clean claims and predictable payment cycles
- Fewer patient complaints because coverage is straightforward
Why most practices choose PAR
Approximately 98% of physicians in the U.S. are PAR because it ensures:
- Smooth billing
- Fewer denials
- Predictable reimbursement
- Easier patient communication
2. Non-Participating Provider (Non-PAR)
Definition
A non-participating provider is enrolled in Medicare but may choose per claim whether to accept assignment.
When You Accept Assignment
Billing works similarly to PAR, but:
- You are paid at 95% of the PAR rate
- Secondary insurance will pay normally
- Claims still crossover
When You Do NOT Accept Assignment
This is where billing becomes more complex:
Billing Impact:
- You may charge up to 115% of the Medicare allowable (the “limiting charge”)
- You collect the full amount from the patient upfront
- You must still send the claim to Medicare
- Medicare reimburses the patient directly
- Secondary insurance usually considers payment only after Medicare adjudication
Common Problems:
- Slower patient reimbursement
- Higher risk of patient frustration
- Increased front-desk collection demands
3. Opt-Out Provider Status
Definition
A physician who opts out of Medicare is completely outside the Medicare program for a minimum of two years.
You:
- Do not submit claims to Medicare
- Must have patients sign a private contract
- Set your own rates (not tied to the Medicare fee schedule)
- Bill patients directly
- Cannot receive Medicare reimbursement in any setting
Billing & Compliance Impact
- No Medicare claims allowed
- You cannot submit claims “just for secondary”
- Private contracts must be retained for six years
- Opt-out is provider-specific (not practice-wide)
How Secondary Insurance Works With Each Medicare Status (Updated & Most Important for Billing)
Secondary insurance—Medigap, employer-sponsored retiree plans, Medicaid as secondary, or commercial secondaries—depends heavily on Medicare’s adjudication process.
Here’s how it works in each scenario ⬇️
PAR Provider + Secondary Insurance
Smoothest workflow for billing.
- Medicare pays first
- Claim crosses automatically to secondary
- Secondary pays their portion
- Patient owes remaining copay or deductible
Benefits:
- Fastest payment
- Minimal patient confusion
- Cleanest RCM workflow
Non-PAR Accepting Assignment + Secondary Insurance
Works almost exactly like PAR:
- Medicare pays you
- Claim crosses over
- Secondary pays normally
- Still RCM-friendly
Non-PAR NOT Accepting Assignment + Secondary Insurance
- Patient pays upfront
- You submit claim to Medicare
- Medicare reimburses the patient directly
- Secondary insurance may or may not pay
- Many secondaries require Medicare’s EOB showing patient payment + limiting charge rules
⚠️ Creates billing complexity
⚠️ Need to collect payments up front
⚠️ Higher administrative burden
Opt-Out Provider + Secondary Insurance
This is where practices often get confused.
General rule:
If Medicare does not adjudicate the claim, most secondary insurers will not pay.
However—based on real-world billing experience and payer contract variations—some secondary plans may still pay.
Secondary insurers that sometimes pay for opt-out providers:
- Large employer-sponsored retiree plans
- Some do not require Medicare adjudication
- They pay based on their own allowable charge schedules
- Commercial secondary plans with flexible plan language
- Some pay based on UCR or plan-allowable rates
- Medicaid-as-secondary (state dependent)
- Some state Medicaid programs reimburse based on Medicaid rules, ignoring Medicare’s involvement
- Medicare Advantage (MA) – Special Case
- MA is a commercial contract
- Opt-out does NOT automatically remove you from MA networks
- Payment depends on your MA contract or out-of-network rules
What practices need to know for billing
- Do not assume secondary will pay
- Payment is not guaranteed or consistent
- Secondary coverage becomes plan-specific
- Patient education is critical
Correct language for compliance:
“While Medicare will not pay for opt-out services and most secondary insurers require Medicare adjudication, some employer or commercial secondary plans may reimburse depending on individual plan rules.”
Comparison Chart for Billing & Reimbursement
| Provider Status | Medicare Pays? | Secondary Pays? | Clean Claims? | Patient Can Submit Claims? | Billing Complexity Level |
|---|---|---|---|---|---|
| PAR | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes | ⭐ Easy |
| Non-PAR (Accept Assignment) | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes | ⭐ Easy |
| Non-PAR (No Assignment) | ✅ Pays patient | ⚠️ Sometimes | ❌ No | ✅ Patient submits | ⚠️ Medium |
| Opt-Out | ❌ No | ⚠️ Rarely | ❌ No | ❌ Not allowed | ❌ High |
Why Understanding Medicare Status Matters for Revenue Cycle Management
Choosing PAR, Non-PAR, or Opt-Out affects:
- Clean claim rates
- Secondary payments
- Front-desk collections
- Patient financial responsibility
- Denial rates
- Cash flow timelines
- Billing compliance
- Credentialing decisions
Accurate knowledge ensures better financial performance and fewer patient billing issues.
References
- Medicare Interactive – Definitions of PAR, Non-PAR, Opt-Out
https://www.medicareinteractive.org/ - Kaiser Family Foundation (KFF) – Data on Medicare opt-out rates
https://www.kff.org/medicare/how-many-physicians-have-opted-out-of-the-medicare-program/ - Physician Side Gigs – Guidance on opting out of Medicare
https://www.physiciansidegigs.com/opting-out-of-medicare - CMS Provider Enrollment & Certification
https://www.cms.gov/Medicare/Provider-Enrollment-and-Certification/MedicareProviderSupEnroll - CMS Claims Processing Manual
https://www.cms.gov/Regulations-and-Guidance/Guidance/Manuals/
Need Help With Medicare Billing or Enrollment Strategy?
At NatRevMD, we help practices:
✅ Understand Medicare enrollment options
✅ Improve reimbursement and claim workflows
✅ Reduce denials and clean up AR
✅ Correctly bill secondaries in complex Medicare scenarios
✅ Avoid costly Medicare compliance mistakes
If your practice wants stronger revenue cycle performance—or needs guidance on Medicare participation decisions—we’re here to help.
👉 Visit NatRevMD.com to book a strategy call
