Aetna medical billing guide: claims processing and reimbursement

How an Aetna claim moves from visit to payment

Every Aetna claim passes six checkpoints: eligibility, coding, scrubbing, submission, adjudication, and payment posting. A mistake at the first one costs the same as a mistake at the fifth. You just find out about it weeks later.

Most denied claims were broken before they left your office. A wrong member ID. A missing referral. A modifier that doesn't match the procedure. Aetna didn't create those problems. It found them. That is good news, because a problem you created is a problem you can stop.

Verify eligibility before every visit

Use Availity to check eligibility each time you see a patient, not just annually. Jobs change, carriers change, and there is no notice letter of coverage loss. The 271 response contains active status, copay, remaining deductible and whether the member is on a commercial, Medicare Advantage or Medicaid product. And the last point is a big one. Different products have different rules for filing and disputing.

Here are three things the response doesn’t always spell out: Is this service pre-approved? Is the member restricted to a particular network tier under the plan? Is there another payer before Aetna? Some of the quiet denials are actually errors in the coordination of benefits. Bill Aetna first when it is secondary and the claim bounces, while your filing clock keeps ticking.

Submit clean claims the first time

The fastest way is to file electronically. Submit professional claims in 837P format through your clearinghouse or directly through Availity. Facility claims in 837I format. Paper claims on the CMS-1500 or UB-04 are still valid, but add additional processing time and a re-keying phase where errors can occur.

Double-check each fact before publication. Ensure billing and rendering NPI numbers match what is currently on file with Aetna. Ensure diagnosis codes match the procedure. Ensure units match the code description. Apply modifiers as required by policy. Aetna’s coding edits pay special attention to modifiers 25 and 59, so include the note that confirms a separate and distinct service before the claim is denied.

Then you read your acceptance reports. A clearinghouse rejection and a payer denial look the same on a dashboard but are different events. Because a denied claim never entered Aetna’s system, no adjudication ever began. But your filing deadline kept moving. Fix same-day rejections and log the cause so tomorrow’s batch doesn’t have the same error.

Know your timely filing window

The filing window for most participating Aetna contracts is 90 days from the date of service. Out-of-network windows are longer and vary by plan, so the number in your agreement is more important than any number in a blog post, including this one. Write the contract. Put the deadline where the billing team can see it.

Two habits protect you. Submit within a few days of the visit instead of batching at month's end. And keep evidence of filing for each claim: the clearinghouse acceptance report with the date and claim ID. Aetna denies a claim as late whenever it can't find the original submission, and that report is the document that reverses the denial.

Corrected and secondary claims carry their own timing, often tied to the original decision date or the primary payer's EOB. The original 90-day period does not start over.

How Aetna adjudicates and pays

Once accepted, Aetna performs automated edits on the claim for eligibility, benefits, authorisation, medical policy and coding. Passed claims are paid at your contract rate, less patient cost sharing. Claims that don’t succeed are either denied or pended on records.

Payment comes in the form of an 835 ERA with EFT. If you are not enrolled in electronic remittance, you will receive a paper EOB and a cheque. Sign up for both electronic options. ERA allows you to automatically post payments and read adjustment codes on the day the money arrives.

Learn the difference between CARC and RARC codes. The CARC gives the category of the adjustment: CARC 45 is the contractual write-off, CARC 1 is the deductible, CARC 197 is a missing authorization. The RARC adds the detail. Reading both takes thirty seconds and decides whether you correct, appeal, or bill the patient.

Why Aetna denies claims

A brief list of reasons leads to the majority of denials.

Eligibility issues take precedence: terminated coverage, an incorrect member ID, or another payer identified as primary. Authorisation issues are as follows. The service either did not have prior authorisation or the authorisation was for different codes or dates than those on the claim. Coding issues can be modifier conflicts, bundled services, diagnoses not supporting medical necessity, and units above the policy limitation. The list is complete with filing issues: late submissions, duplicates and missing rendering provider data.

Every category requires its own solution. Eligibility denials typically result in either an update to coverage or a shift to patient responsibility. Authorisation denials require a retro-authorization request or an appeal accompanied by clinical notes. Coding denials require either a corrected claim, an appeal accompanied by documentation, or a combination of both. Denials for timely filing require evidence of submission. Resubmitting all four keeps practices trapped in a cycle.

Aetna – Denials for monthly reason codes. If one code covers a large part, then fix the front-end problem instead of reopening the same claims over and over.

Try this. Pull your last fifty Aetna denials and break each one down into either a front desk error, a coding error or a billing error. Most practices determine the split points for a single stage where a fix starts to pay off.

Dispute and appeal steps that work

You have 180 calendar days from the date of the initial claim decision to file a dispute with Aetna, which will try to respond within 45 business days. If the dispute fails, there is the appeal. You have 60 calendar days from the date of the previous decision to file it, which is extended to 180 days for medical necessity or utilisation review issues. Aetna will answer appeals within 60 business days. Medicare provider appeals work on a 65-day window, and some states have their own exceptions.

If possible, file through Availity. An appeal form is not required for online submissions. Appeals sent by mail or fax require an appeal form. Aetna can't process appeals without an appeal form. Attach the original claim, the denial or EOB, the medical records, and a one-page letter that explains what you want changed and why. If you have a contract section or medical policy number, please include it.

Be specific. "Please reconsider" loses. "CPT 99214 with modifier 25 was a significant, separately identifiable service, see the attached note on page 2" wins.

25", which was a significant, separately identifiable service, see the attached note on page 2."

Medicare Advantage and Medicaid plans follow different rules

Aetna is not a one-rule book. Commercial, Medicare Advantage and Aetna Better Health Medicaid plans have separate filing and dispute terms. Participating providers have 180 days from the date of determination to dispute Aetna Better Health Notices unless otherwise stated in the provider agreement. Medicare Advantage claims from non-contracted providers typically get up to 12 months to file.

Apply the commercial 90 days to every Aetna claim and you will leave money on the table. Apply a longer window to a commercial claim and you will lose it. Tag the plan type at registration and let your billing system set the right deadline.

Build a follow-up routine that catches underpayments

Each week track four numbers: first pass acceptance rate, denial rate, days in A/R and net collection rate versus your contracted allowable. Assign one person to own Aetna follow-up. Check the status on Availity for a claim not paid within 30 days of acceptance. 45 days someone rings

Compare each payment to your Aetna fee schedule. An underpayment is a denial in disguise, and most practices never pursue it. Create a rule that any payment that comes in at a rate not equal to the contract rate is put on a review list, and that list is worked on each week. Small differences can quickly accumulate across hundreds of claims.

Frequently asked questions