Authorization in Medical Billing: Types, Processes, and Denial Prevention

Introduction

Authorization in Medical Billing is the insurer’s approval for a healthcare service. However, late approvals, incorrect details, or delayed claims often lead to denials and lost revenue. Therefore, healthcare organizations should learn each payer’s guidelines to prevent these issues.
In 2026, CMS changed the time limits for prior authorization. It also required payers to explain denials. As a result, doctors, clinics, and hospitals need to improve how they handle authorizations. This guide covers the five common types of authorization, the usual reasons for denials, and best practices for a smooth process.

What Is Authorization in Medical Billing?

Authorization in Medical Billing is the approval an insurance company gives for a specific healthcare service. Depending on the payer, providers can obtain it before, during, or after treatment.
The authorization process includes verifying that there are benefits available under a patient’s insurance policy, submitting clinical information to support the medical necessity of the procedure(s) being requested, obtaining a decision from the payer as to whether or not they will authorize coverage of the procedures, documenting the terms of the authorization, and communicating with the patient regarding their responsibility for out-of-pocket costs associated with the approved treatments.

Why Is Authorization Important for Revenue?

• Reduce claim denials caused by missing approvals.
• Avoid payment delays and billing rework.
• Confirm coverage requirements before treatment.
• Improve patient access to medical services.
• Maintain accurate billing records.

Types of Authorization in US Medical Billing

Healthcare providers commonly handle five types of authorization based on when and why the payer reviews a service.

Type	When Required	Purpose
Prior Authorization	Before treatment	Obtain approval for a service.
Concurrent Authorization	During treatment	Review continued medical care
Retrospective Authorization	After treatment	Review services already provided
Referral Authorization	Before specialist care	Confirm required referral approval.
Specialized Authorization	Depends on payer rules	Meet additional review requirements

Prior Authorization 

Prior Authorization is also called pre-authorization or preapproval. It is a process in which healthcare providers obtain approval from a patient’s insurance company before providing certain medical services, procedures, medications, or treatments. Providers must give the payer treatment details and supporting clinical documentation for review.

How Does Pre-authorization in Medical Billing Work?

• First, evaluate the patient’s insurance coverage and perks.
• Next, confirm whether the service needs pre-authorization.
• Then collect the medical data, such as diagnosis and test results.
• After that, you must submit it using the insurer’s website or chosen method.
• Check the status. If the insurer asks for more documentation, send it promptly.
• If authorized, record the authorization number and period of validity. Then check this data before you provide any service.

Concurrent Authorization (Concurrent Review)

When a patient’s medical service needs are assessed continuously throughout therapy, this is called concurrent authorization. This mostly applies to cases of patients’ admission into hospital, rehabilitation, and care in behavioral health.
For instance, a hospital may get approved for a 3-day stay. The hospital, if the need arises and the patient’s condition necessitates care beyond the first 3 days, submits an updated clinical report to request permission for a number of days in which the patient remains in the hospital authorized.

The process includes:

• Monitoring approved treatment dates.
• Submitting updated clinical documents.
• Requesting additional treatment days or units.
• Tracking payer decisions.
• Informing clinical teams about approval status.

Timely concurrent reviews help hospitals steer clear of payment problems tied to services that ran past the approved time.

Retrospective Authorization

Retrospective Authorization is also known as Retro Authorization or Post-Service Review. It is obtaining authorization from the payer after providing the service. Providers use it when they could not gain approval in advance. But it only works if the payer accepts after-the-fact requests.

For example, a patient may need emergency treatment before the hospital can obtain approval. The billing team may submit medical records and supporting documents for a retrospective review.

Post-Authorization in Medical Billing

It refers to the payer’s review or approval after treatment. The process may involve:

• Reviewing medical records.
• Confirming medical necessity.
• Submitting supporting documents.
• Following payer deadlines.
• Requesting claim reconsideration when permitted.

Retro authorization does not guarantee payment. Providers must check payer policies and submission deadlines.

Referral Authorization in Medical Billing

Referral Authorization is the official approval to see a specialist or other doctor. For example, most HMO plans won’t let you book a cardiologist directly. First, you have to go to your primary care doctor and acquire a referral.

• Referral authorization: Validates approval for specialist visits.
• Prior authorization: This is when the insurer approves a specific treatment or service.

Some plans require both. And you may need a referral to the specialist and a separate approval for the service as a consequence. Billing teams must check each criterion separately.

Specialized Authorizations

Certain medical services require additional payer reviews beyond standard authorization.

Common examples:

• Pre-claim review: The payer reviews your papers before you file a claim, usually for specified services.
• Medical necessity review: The payer reviews whether the service fits coverage criteria.
• Authorization of admission: Authorization for certain hospital admissions.
• Drug approval: Authorization of some prescription pharmaceuticals and specialty drugs.

Each insurer has its own rules. Providers should therefore refer to the most up-to-date recommendations before treating a patient.

Which Services Typically Require Authorization?

Insurance companies may require authorization for different services based on plan rules and medical policies.

Service Category	Common Examples
Diagnostic imaging	MRI, CT scans, PET scans
Surgical procedures	Elective and outpatient surgeries
Hospital services	Planned inpatient admissions
Rehabilitation	Physical and occupational therapy
Durable medical equipment	Wheelchairs and oxygen equipment
Specialty medications	Selected high-cost drugs
Behavioral health	Certain inpatient treatments

Common reasons for authorization denials

• Lack of documentation: Clinical documentation does not support the request.
• Medical necessity issues: The payer does not find sufficient clinical rationale.
• Wrong patient information: Member ID or insurance information is incorrect.
• Inactive coverage: The patient’s insurance is inactive.
• Incorrect codes: Diagnosis or procedure codes do not correspond to the service requested.
• Provider not in network: The benefit is not applicable because the provider is not a network provider.
• Expired authorization: The authorization period was short-lived.
• Maxed out: The request is higher than the approved visits or treatment units.
• Late filing: The provider was late to meet the deadline by the payer.

How to Handle Authorization Denials: Peer-to-Peer and Appeals

There is a system that healthcare providers can use if the authorizations are denied, one of which is a process of systematically handling the denials of the authorization.

Step 1: Find out the reason for the denial.

Read and understand the denial letter from the payer and figure out if anything is missing, if medical necessity is an issue, or if administrative difficulties are present.

Step 2: Correct and submit again.

Correct and resubmit the information in case of a mistake or if something is missing. The period should not be extended beyond what the payer allows.

Step 3: Apply for a peer-to-peer review.

During the peer-to-peer review, the doctor who is treating the patient communicates face-to-face with the medical reviewer of the payer to discuss the health issues of the patient and also the required ‍‍‍treatment.

Step 4: Challenge the decision.

If the payer denies again, appeal and send in your medical records, doctor’s notes, test results, and clinical justification.

Step 5: Track the final decision

Track appeal dates, payer answers, and final results. Communicate the decision to the teams involved.

CMS Changes and Implementation Timelines in 2026

The CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F) updates prior authorization processes for some health plans.

Important updates include:

January 1, 2026: Faster Decision Timelines

Impacted payers must generally respond within:

• 72 hours for expedited or urgent requests.
• Seven calendar days for standard requests.

January 1, 2026: Grounds for Refusal

Affected payers will need to have adequate rationale for denial of a prior authorization request for a non-drug item or service that is required to be approved under the regulation before declining the request. 

This gives providers a better understanding of the rationale behind the original denial decision, which may allow for a higher quality of future resubmission or appeal efforts.

January 1, 2027: Pre-Authorization APIs

Impacted payers must also implement an electronic Prior Authorization Application Programming Interface (API) that allows providers to determine whether there are any authorization requirements for an item/service, submit a prior authorization request electronically to the payer, and receive a determination from the payer.

Best Practices to Handle Authorizations

Here are some techniques to help healthcare providers keep up with authorization management: 

• Verify insurance eligibility/benefits before scheduling.
• Learn the policies of each payer. Maintain a current list of authorization criteria for each plan.
• Be thorough with documentation. Attach clear descriptions of the services, diagnostic codes, and clinical comments.
• Track the progress of your request, step by step, after you have submitted it. Keep an eye on pending items and approval and expiration dates.
• Verify clearances before therapy. Verify that the patient, provider, and service information corresponds to the request.
• Update nursing, front desk, and billing staff. This avoids duplicate work.
• Look for trends in denials. Correct any mistakes if they continue to happen.
• Electronic workflows. They eliminate the manual process and allow you to talk directly to payers.

Conclusion 

Managing authorizations assists healthcare providers in reducing avoidable denied claims, avoiding delayed payments, and increasing their overall success in managing their revenue cycle. By understanding each payer’s unique requirements and keeping their authorization information up-to-date, healthcare providers can increase the efficiency of their billing operations.

To support these efforts, Velan Healthcare Services (Velan HCS) provides comprehensive outsourced revenue cycle management solutions, including authorization support, insurance verification, medical billing, claims processing, denial management, and accounts receivable follow-up. With over 19 years of industry experience and expertise across 50+ medical specialties, we help healthcare providers simplify complex administrative processes, minimize revenue leakage, and optimize their financial performance, allowing them to focus more on delivering quality patient care.

FAQ

What is authorization in medical billing? 

Authorization in Medical Billing is approval from the insurance company for a specific medical service. Some payers require it before treatment. However, others require it during or after treatment.

What is meant by pre-authorization and post-authorization?

Pre-authorization takes place before treatment to obtain payer approval. Post-authorization involves a review or approval request after the service has been provided, when the payer allows it.

What is a prior authorization number in medical billing?

A Prior Authorization number is a reference number the insurer gives when it approves a service. It helps the provider and payer track the approval. Billing staff must record the authorization number, approved procedure, service dates, visit count, and provider data. Plus, the right number on the claim prevents denials.

What is a reverse authorization?

Reverse authorization is not a standard payer term. It may refer to retroactive authorization, where a provider requests approval after providing a medical service.