The Short Answer
Check eligibility when the visit is booked, again one or two days before, and confirm the card at check-in. Each time, confirm that coverage is active on the date of service and record what the patient will owe. Most eligibility denials come from skipping one of these checks.
What to Confirm Every Time
| Item | Why it matters |
|---|---|
| Coverage active on the date of service | Prevents CO-27 and CO-26 denials |
| Name, date of birth and member ID match exactly | Prevents CO-31 denials |
| Plan type and payer (including Medicare Advantage or Medicaid plans) | Sends the claim to the right payer and avoids CO-109 |
| Your network status with the plan | Out-of-network care can cost the patient much more |
| Deductible remaining, copay, coinsurance and out-of-pocket maximum | Lets you collect the right amount at the visit |
| Prior authorization or referral needs | Missing authorizations cause some of the costliest denials |
| Other insurance (coordination of benefits) | Prevents CO-22 denials and delays |
Step by Step
- Collect the card and photo ID at scheduling. Get the member ID, group number and the subscriber's name and birth date.
- Run an electronic eligibility check (a 270 request) through your clearinghouse or the payer portal. Under industry operating rules, real-time checks should come back within 20 seconds.
- Read the response (the 271). Confirm active coverage, plan dates and the benefits for the service type you are providing.
- Check the service, not just the plan. Coverage for an office visit does not mean coverage for physical therapy, imaging or behavioral health.
- Check authorization and referral rules for the planned service.
- Look for other coverage. If the response lists another payer, sort out who pays first before the visit.
- Save the proof: a copy of the response or the call reference number, with the date and staff name.
- Tell the patient what they will owe before the visit, and collect the copay at check-in.
Ways to Check Eligibility
| Method | Best for | Notes |
|---|---|---|
| Clearinghouse real-time check (270/271) | Most payers, in bulk or one at a time | Fast and saves a record automatically |
| Payer provider portal | Benefit details and authorization rules | One login per payer |
| Multi-payer portal, such as Availity | Checking many commercial payers in one place | Free for providers with many plans |
| Phone or IVR | Unusual benefits or unclear responses | Write down the reference number |
| Medicare (HETS) or Medicare contractor portal | Original Medicare patients | Medicare accepts only the MBI |
| State Medicaid portal | Medicaid and Medicaid managed care | Coverage can change at renewal |
Reading a 271 Response
The eligibility response uses short codes in a field called EB01. These are the ones you will see most:
| Code | Meaning | What to do |
|---|---|---|
| 1 | Active coverage | Check the plan dates and service benefits |
| 6 | Inactive | Ask the patient for current coverage before the visit |
| A | Coinsurance | Note the percentage the patient owes |
| B | Copayment | Collect at check-in |
| C | Deductible | Note the remaining amount, not just the yearly total |
| G | Out-of-pocket maximum | If met, the patient owes little or nothing |
| I | Non-covered | Tell the patient before the service |
| L | Primary care provider | Check that you are the assigned PCP or have a referral |
| R | Other or additional payer | Sort out coordination of benefits |
| U | Contact the listed entity | Benefits are managed elsewhere, often by a carve-out vendor |
| V | Cannot process | Re-check the details or call the payer |
Medicare Eligibility Tips
- Medicare's eligibility system (HETS) accepts only the MBI, the Medicare Beneficiary Identifier.
- The response can show Part A and Part B dates, a Medicare Advantage plan, other primary insurance, hospice periods and preventive service dates.
- If the patient is in a Medicare Advantage plan, bill that plan, not Original Medicare.
- If the response shows QMB status, do not bill the patient for Medicare deductibles or coinsurance. Federal rules ban it.
- Check the remaining Part B deductible before you estimate the patient's share.
Common Mistakes
- Checking only once, at booking, for a visit weeks later.
- Reading "active" but not the coverage start and end dates.
- Checking the plan but not the benefits for the actual service.
- Missing a second insurance listed on the response.
- Not saving proof of the check, which you may need for an appeal.
Related: how to reduce claim denials and our primary payer decision tool.
Sources: ASC X12 element 1390, Eligibility or Benefit Information Code (271 EB01); CMS HIPAA Eligibility Transaction System (HETS) 270/271 documentation, MBI requirement; CAQH CORE eligibility and benefits operating rules (20-second real-time response).
Frequently Asked Questions
How do I verify a patient's insurance eligibility?
Check coverage at scheduling and again one or two days before the visit. Use the payer's portal, a multi-payer portal such as Availity, or a real-time 270/271 check through your clearinghouse. Confirm active coverage on the date of service, network status, deductible, copay, coinsurance, prior authorization needs and any other insurance.
What does EB01 code 1 mean on a 271?
Code 1 means active coverage. Code 6 means inactive. Other common codes are A (coinsurance), B (copay), C (deductible), G (out-of-pocket maximum) and R (another payer).
How do I check Medicare eligibility?
Through your clearinghouse, which connects to Medicare's HETS system, or through your Medicare contractor's provider portal. Medicare accepts only the Medicare Beneficiary Identifier (MBI) for these checks.
How often should eligibility be verified?
At every visit. Coverage can change from month to month because of job changes, unpaid premiums or Medicaid renewals. Re-check before costly scheduled services even if you checked at booking.
What denials happen when eligibility is not checked?
The most common are CO-27 (coverage ended), CO-26 (coverage not started), CO-31 (patient not identified), CO-109 (wrong payer) and CO-22 (another plan should pay first).
Reviewed by Hassan Raza Awan, Founder — 4+ years of hands-on U.S. medical billing experience. General billing information — verify against current CMS guidance and your payer contracts.
Where eligibility fits: medical billing process, step by step. Found the right payer late? Check the filing deadline with our TFL calculator.
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