> ## Documentation Index
> Fetch the complete documentation index at: https://mso.getlemma.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Get prior authorizations
> Identify auth-required services per payer, submit through the right channel, track turnaround, capture the number on the claim, and handle peer-to-peer reviews.
**Prior authorization** is a payer's advance approval for a service. Missing it produces CARC 197, a contractual denial you generally cannot bill the patient for. The most common failure is not failing to obtain one; it is obtaining one and never getting the number onto the claim.
## Prerequisites
* Eligibility verified — see [Verify eligibility](/guides/billing/verify-eligibility)
* A per-payer list of auth-required services
* A field in the PM system where the auth number lives
* Portal access for each payer
## Steps
Payers publish these, and they change. Build a reference list of the CPT codes you commonly perform, marked by payer for whether authorization is required.
Review it quarterly. Payers add codes to the list without much notice.
Not the day before. Authorization turnaround ranges from same-day to several weeks, and a request submitted late means either a rescheduled patient or an unbillable service.
| Channel | Notes |
| ------------------- | ----------------------------------------------------------------- |
| **Payer portal** | Usually fastest; the default for most payers |
| **278 transaction** | The X12 standard, where your system and the payer both support it |
| **Phone** | For urgent requests; get a reference number |
| **Fax** | Yes, still. Some payers only. Keep the transmission confirmation. |
Include: patient and member ID, diagnosis, the specific CPT codes, the clinical justification, the requesting and rendering providers, the facility, and the anticipated date.
Payers have expedited pathways where a delay would jeopardize the patient. Use them when genuinely applicable, and know that misusing them erodes their availability.
A tracking log with: patient, service, payer, submission date, expected turnaround, follow-up dates, status, auth number, valid date range, and authorized units.
Follow up before the anticipated service date, not after.
**This is where the process most often fails.** The authorization is obtained, the number is written in the clinical note, and it never reaches the billing field, so it never reaches the 837, and the claim denies CO-197 exactly as if no authorization existed.
Put it in the **structured field** the claim pulls from. Then build a **scrubber edit** that blocks submission when a CPT on the payer's auth list has no authorization number. A structural control works on a Friday afternoon; a checklist item depends on a person.
Before the service: right CPT codes, right units, right date range, right rendering provider, right facility. An authorization for one procedure code does not cover a different one, and an expired date range denies the same as no authorization.
When authorization is denied, most payers offer a **peer-to-peer** — your clinician speaks with the payer's reviewing physician.
Prepare: the clinical rationale, relevant guidelines, prior conservative treatment tried, and the specific coverage criterion at issue. Schedule promptly, since the window is limited. A prepared peer-to-peer overturns a meaningful share of authorization denials.
## Retro-authorization
Some payers permit authorization after the service in defined circumstances — urgent or emergent care, or where eligibility was in question at the time.
Ask; don't assume. Where available, there is a deadline. Where unavailable, your remaining options are an appeal on medical necessity or a write-off.
## What you cannot do
**A CO-197 denial cannot be billed to the patient.** Group code CO means contractual obligation. The patient did nothing wrong; your practice failed to obtain something the contract required.
Billing the patient for it breaches your participation agreement and, in many states, violates regulation. See [The 835](/concepts/payments/understanding-835s).
## Verify it worked
* [ ] Per-payer auth-required list built and reviewed quarterly
* [ ] Request triggered at scheduling
* [ ] Submitted through the payer's preferred channel, with confirmation retained
* [ ] Tracked to an answer
* [ ] Auth number in the **structured PM field**, not only the clinical note
* [ ] Scrubber edit blocking submission when an auth is required and missing
* [ ] Authorization verified against CPT, units, dates, provider, and facility before the service
* [ ] Peer-to-peer process defined and used
## Common failure modes
| Failure | Consequence |
| ------------------------------------------- | ----------------------------------------- |
| Auth obtained but not captured on the claim | CO-197 despite having the authorization |
| Requesting too late | Rescheduled patient or unbillable service |
| Auth doesn't match the service billed | Denial |
| Authorization expired before the service | Denial |
| Stale auth-required list | Denials on newly added codes |
| No scrubber edit | Relies entirely on human memory |
| Billing the patient for a CO-197 | Contract breach |
| Not using peer-to-peer | Losing overturnable denials |
## Related topics
- [Your first denial](/start/first-90-days/work-your-first-denial.md)
- [Verify eligibility and benefits](/guides/billing/verify-eligibility.md)
- [Submit clean claims](/guides/billing/submit-clean-claims.md)
- [File appeals](/guides/billing/file-appeals.md)
- [Claim denials, explained](/concepts/payments/claim-denials.md)
- [The life of a claim](/concepts/payments/claim-lifecycle.md)
- [CARC codes (Claim Adjustment Reason Codes)](/reference/edi/carc-codes.md)
- [Denial code playbook](/reference/edi/denial-code-playbook.md)