How to Bill When a Provider Isn't Fully Credentialed Yet

:::info Quick answer You cannot legally bill under a provider's NPI until they are fully credentialed with a payer. To maintain cash flow, hold claims until an effective date is issued, utilize strict incident-to billing under a supervising physician, or bill out-of-network with explicit signed patient consent. :::

A new orthopedic surgeon walks into your clinic on a Monday morning. Her schedule is packed with 15 patients. There is just one massive operational problem: her payer enrollment applications are still sitting in "pending" status across three different commercial portals, and Medicare hasn't issued a final approval letter yet. Welcome to the credentialing gap.

Every billing manager has faced this scenario. Provider recruitment moves faster than payer enrollment. In late 2026, despite the rollout of streamlined digital portals like PECOS 2.0, the average commercial credentialing timeline still hovers between 60 and 120 days. Practice owners hate seeing an empty schedule, so they push new hires into the clinic immediately. Revenue cycle teams are then left holding the bag, trying to figure out how to get paid for those services without triggering an audit.

Many practice owners assume that billing before credentialing is complete is just a matter of slapping the medical director's NPI on the claim. Do that, and you are committing wire fraud. Billing a service under a provider who did not actually perform the service—unless strict specific exceptions are met—violates the False Claims Act.

Let's break down exactly how you can legally manage this gap, when you can use workarounds like "incident to" or locum tenens, and how to protect your timely filing limits when you are forced to hold claims.

The "Incident To" Loophole (And Why It Is Dangerous)

The most common tactic clinics attempt when a new physician or mid-level provider lacks credentialing is billing "incident to" a fully credentialed supervising provider. While this is entirely legal under Medicare rules (and adopted by many commercial payers), the compliance guardrails are incredibly rigid.

CMS defines "incident to" services as those furnished as an integral, although incidental, part of the physician's personal professional services in the course of diagnosis or treatment of an injury or illness. If your uncredentialed provider sees a patient, you can bill under the credentialed physician's NPI only if you meet every single one of the following criteria.

The Direct Supervision Requirement

For 2026, direct supervision rules dictate that the supervising physician must be present in the office suite and immediately available to provide assistance and direction throughout the time the service is performed.

They do not need to be in the exact exam room, but they cannot be at the hospital doing rounds, across the street grabbing lunch, or working from home. If your uncredentialed nurse practitioner (NP) is seeing patients on a Friday afternoon and the fully credentialed supervising physician leaves the building at 2:00 PM, any subsequent services billed incident-to are fraudulent.

New Patients vs. Established Patients

This is where most billing departments fail audits. You cannot bill a new patient visit (CPT codes 99202-99205) incident-to.

The credentialed supervising physician must perform the initial service, establish the diagnosis, and outline the initial plan of care. The uncredentialed provider can only see the patient for follow-up visits related to that specific, established problem (CPT codes 99211-99215). If an established patient presents with a completely new problem—say they are being treated for hypertension but come in complaining of new knee pain—the uncredentialed provider cannot treat the knee pain and bill it incident-to. The supervising doctor must step in, evaluate the new problem, and establish a new plan of care.

Fee-For-Time Compensation (Modifiers Q5 and Q6)

Old-school billers still call this "locum tenens," but CMS officially refers to it as Fee-For-Time Compensation Arrangements. Practices often try to use this rule to bill for a newly hired, uncredentialed physician by treating them as a locum tenens for the practice owner.

This is highly scrutinized. Modifier Q6 is exclusively for situations where a regular physician is absent for reasons such as illness, pregnancy, vacation, or continuing medical education, and a substitute physician takes their place temporarily.

The Rules for Modifier Q6

If you use modifier Q6 to bill for an uncredentialed physician, you must meet these conditions:

• The regular physician must be unavailable to provide services.
• The Medicare patient has arranged or seeks to receive services from the regular physician.
• The substitute physician does not provide the services to Medicare patients over a continuous period of longer than 60 days.
• The regular physician pays the substitute on a per diem or similar fee-for-time basis.

You cannot use modifier Q6 to mask an uncredentialed new hire who is adding capacity to your clinic. If Dr. Smith is hired to open a new patient panel and is working alongside Dr. Jones, Dr. Smith is not a substitute. Billing Dr. Smith's services under Dr. Jones' NPI with a Q6 modifier will trigger massive recoupments during a Recovery Audit Contractor (RAC) review.

Reciprocal Billing (Modifier Q5)

Modifier Q5 is used for reciprocal billing arrangements, where two physicians cover for each other on an informal, reciprocal basis (e.g., weekend on-call coverage). Like Q6, this is strictly limited to 60 continuous days and requires the regular physician to be absent. It offers zero help for onboarding a permanent new hire whose PECOS application is stuck in processing.

Holding Claims: The Safest Strategy

For 90% of situations involving an uncredentialed provider, the only legally sound strategy is to hold the claims. You stockpile the superbills and wait until the payer issues the official effective date of enrollment.

However, holding claims creates a ticking time bomb with Timely Filing limits. Every payer has different rules regarding retroactive effective dates and timely filing windows.

Medicare's 30-Day Retroactive Rule

Medicare is generally the most predictable payer. Under current CMS guidelines, a provider's effective date of billing can be made retroactive up to 30 days prior to the date the MAC receives the enrollment application, assuming the provider was fully licensed and rendering services during that time.

If Dr. Adams starts seeing Medicare patients on October 1, 2026, and your credentialing team submits his application via PECOS on October 15, 2026, his effective date will cover the October 1 visits. You simply hold the claims until the MAC approves the application and issues the Provider Transaction Access Number (PTAN), then drop the claims.

Commercial Payer Realities

Commercial networks are far less generous. Many do not offer retroactive effective dates. If UnitedHealthcare approves your application on November 15, November 15 is your effective date. Any services rendered between October 1 and November 14 will be processed as out-of-network.

Here is a breakdown of how major payers typically handle credentialing gaps in 2026:

Out-of-Network Billing and the No Surprises Act

If a commercial payer refuses to backdate the effective date, the provider is technically out-of-network for those dates of service.

You can bill the patient directly, but you must navigate the strict regulations of the No Surprises Act (NSA). As of 2026, the enforcement around Good Faith Estimates (GFEs) is severe. If you know a provider is uncredentialed and will be considered out-of-network, you cannot simply surprise the patient with a full-fee balance bill a month later.

Your front desk must inform the patient prior to the visit that the provider is out-of-network. The patient must receive a formal Good Faith Estimate detailing the expected costs, and they must sign an Advance Beneficiary Notice (ABN) for Medicare or a specific financial responsibility waiver for commercial plans, explicitly agreeing to pay out-of-pocket.

Action Plan: Structuring Your Workflow

To survive the credentialing gap without bleeding revenue or inviting fraud investigations, RCM managers need a lockdown procedure. Implement this workflow the moment a new hire signs their employment contract:

• Submit applications 90 days out: Do not wait for the provider's start date. Submit enrollment packets to MACs and commercial payers at least three months before they see their first patient.
• Establish a claim hold queue: Configure your practice management (PM) system to automatically route any charges tied to the new provider's NPI into a specific "credentialing hold" work queue.
• Track timely filing daily: Assign a dedicated biller to monitor the hold queue. If a claim approaches the 60-day mark and the payer has a 90-day limit, prepare to submit the claim out-of-network to generate a denial. You need that CO-29 (Time limit for filing has expired) or CO-16 (Claim lacks information) denial on file to prove you attempted to bill within the window.
• Secure proof of pending status: When you eventually appeal a timely filing denial for an uncredentialed provider, you must prove the delay was the payer's fault. Keep screenshots of the payer portal showing the application as "pending," date-stamped emails from credentialing reps, and certified mail receipts.
• Train the front desk on waivers: Do not let a front desk coordinator tell a patient, "We take your insurance." If the provider is pending, the script must be: "Dr. Smith is currently awaiting final network approval from your insurance. Today's visit will be considered out-of-network. Here is your Good Faith Estimate."

Managing the gap between a provider's start date and their official payer enrollment requires discipline. Resist the urge to aggressively bill under inappropriate NPIs to smooth over cash flow. By strategically holding claims, strictly adhering to incident-to guidelines, and proactively securing patient waivers, you protect the practice's bottom line and its medical license.

Frequently asked questions

Can I bill under the practice owner's NPI if the new doctor isn't credentialed yet?

No, unless you meet strict 'incident-to' requirements. Billing a new patient visit or a new problem under the owner's NPI when the uncredentialed doctor performed the service is a violation of the False Claims Act.

How long does Medicare take to issue a PTAN in 2026?

Through the PECOS 2.0 system, standard Medicare enrollment typically takes 45 to 60 days, though clean applications can process faster. Medicare allows a retroactive effective date up to 30 days prior to the application receipt date.

Can we use Modifier Q6 (Locum Tenens) for a new hire?

No. Modifier Q6 is restricted to temporary substitute physicians covering for a regular physician who is absent due to illness, vacation, or leave. It cannot be used for a permanent new hire expanding the clinic's capacity.

What happens if holding a claim causes us to miss the timely filing deadline?

You should drop the claim right before the deadline to generate a formal denial (often CO-16 or a non-participating denial). Once credentialing is complete, you can appeal the denial with proof that the enrollment application was pending with the payer during the timely filing window.

Does the No Surprises Act apply to pending credentialing?

Yes. If a commercial payer refuses to backdate the effective date, the provider is out-of-network. Under the NSA, you must provide the patient with a Good Faith Estimate and obtain their consent to be billed out-of-network prior to the service.