A new physician joins a practice on August 1. The practice manager tells the owner that the doctor is "credentialed with Aetna" and the owner assumes claims can go out. They cannot. The physician has been credentialed, meaning the plan has verified her training and licenses, but she has not been contracted or loaded, so the claim system does not know she exists, and claims will deny. The owner, who has been in medicine for twenty years, has never had anyone explain the difference. Nobody had to, because his last practice had a credentialing department.
Independent practices do not have that luxury, and the vocabulary matters because each term is a step, and each step has its own timeline and its own failure mode. We put this glossary together for the physicians and office managers who inherit credentialing without training. It is organized in the order the work happens: identity, enrollment, verification, contracting, and maintenance.
Two terms first, since everything else depends on them. Credentialing is the process by which a payer or facility verifies a provider's qualifications: education, training, licensure, board status, work history, malpractice history and sanctions. Enrollment (or contracting, depending on who is speaking) is the process of getting the provider into a payer's network and claim system so that claims can be paid. You can be credentialed and not enrolled. You cannot be enrolled without being credentialed.
Key takeaways
- Credentialing verifies qualifications; enrollment and contracting put the provider in the payer's system; loading is the final data entry step that actually makes claims pay.
- The NPI from NPPES is the identity every other system keys on, and a wrong taxonomy or address there propagates everywhere.
- Medicare enrollment runs through PECOS with the CMS-855 forms and allows a retroactive effective date of up to 30 days before the application was received; most commercial plans do not.
- CAQH attestation every 120 days is the single most common cause of an unexplained commercial hold.
- Delegated credentialing lets a large group or hospital credential its own providers under NCQA standards, which can cut weeks off the process for practices that qualify.
Identity terms
NPI (National Provider Identifier). The ten-digit number assigned to every provider and organization that bills health plans. A Type 1 NPI belongs to an individual. A Type 2 NPI belongs to an organization, such as your practice entity. A group practice needs both: each clinician's Type 1 as rendering provider, the practice's Type 2 as billing provider.
NPPES (National Plan and Provider Enumeration System). The CMS system that issues NPIs and holds the public record for each: name, practice address, mailing address, taxonomy, and, for individuals, license numbers. Payers pull from it. If the address or taxonomy in NPPES is wrong, expect enrollment applications to be returned.
Taxonomy code. A ten-character code describing the provider's specialty and type, such as 207Q00000X for family medicine or 363L00000X for nurse practitioner. Some payers require a specific taxonomy on the claim and will deny when it does not match their record.
TIN and EIN. The tax identification number the practice bills under. A sole proprietor may bill under a Social Security number, though nobody should. Every payer contract is between the payer and a TIN, which is why a physician who moves practices has to be re-enrolled even with the same payer.
Medicare enrollment terms
PECOS (Provider Enrollment, Chain, and Ownership System). The Medicare enrollment system. Applications are submitted online through PECOS or on paper CMS-855 forms and reviewed by the Medicare administrative contractor (MAC) for your jurisdiction.
CMS-855I, 855B, 855R, 855O. The Medicare enrollment forms. The 855I enrolls an individual physician or practitioner. The 855B enrolls a group or clinic. The 855R reassigns an individual's right to receive Medicare payment to a group, which is what lets the practice bill for the physician's services. The 855O enrolls a provider solely to order and refer, without billing. A new physician joining an existing group typically needs an 855I (if not already enrolled) and an 855R.
Reassignment. The arrangement created by the 855R. Without it, Medicare pays the physician directly, not the practice. When a physician leaves, the practice should terminate the reassignment; a stale reassignment can pull the departed physician into the practice's MIPS data and its compare profile.
Revalidation. Medicare requires enrolled providers to revalidate every five years (every three for DMEPOS suppliers). The MAC sends a notice; the due date is also visible in the PECOS revalidation lookup. Missing it leads to deactivation, and a deactivated provider's claims deny until reactivation, with no retroactive payment for the gap.
Effective date and retroactive billing. For physicians and non-physician practitioners, Medicare sets the effective date as the later of the date of filing or the date the provider began furnishing services at the new location, and allows retrospective billing for up to 30 days before the date the application was received (90 days in a declared emergency). This is the one place in credentialing where "we started seeing patients before approval" is recoverable, within limits.
Verification terms
Primary source verification (PSV). Confirming a credential with the body that issued it: the medical school, the state licensing board, the ABMS or AOA board, the DEA. A copy of the certificate is not PSV. Payers and hospitals must do PSV under NCQA and Joint Commission standards, and it is why credentialing cannot be instant.
CAQH ProView (now the CAQH Provider Data Portal). The shared database where a provider enters one application that participating payers pull from. The provider must attest that the data is current every 120 days and must upload current copies of the license, DEA, malpractice face sheet and board certificate as they renew. An expired attestation is invisible to the practice and stops most commercial credentialing cold.
NPDB (National Practitioner Data Bank). The federal repository of malpractice payments, adverse licensure and privileging actions, and exclusions. Payers query it during credentialing. A report there is not disqualifying by itself, but it will draw a request for explanation.
OIG exclusion list (LEIE) and SAM. Lists of individuals and entities excluded from federal health programs. Payers check them at credentialing and, under Medicare rules, practices should check their own staff monthly.
Credentialing committee. The payer's or hospital's peer group that reviews completed files and approves participation, usually on a monthly schedule. "Pending committee" means the file is complete and waiting for the meeting date. Missing the meeting by a day can add a month.
Contracting and loading terms
| Term | What it means | Why it matters to the practice |
|---|---|---|
| Participation agreement (par contract) | The contract between the payer and the TIN setting rates, filing limits, appeal rights and obligations | Rates and terms live here, not in the provider manual; new physicians join under the group's existing contract |
| Fee schedule exhibit | The contract attachment listing allowed amounts by CPT code, or a percentage of a Medicare year | Without it you cannot check underpayments |
| Effective date | The date from which the payer will pay claims for the provider | Most commercial plans do not backdate; visits before this date are usually unpaid or out-of-network |
| Loading (or linking) | The payer's data entry attaching the provider to the TIN, locations and fee schedule in the claim system | The most common reason an "approved" provider's claims still deny; ask for the load confirmation |
| Delegated credentialing | A payer contractually allows a large group, IPA or hospital to credential its own providers under NCQA standards, with periodic audits | Can cut credentialing to days; available mainly to groups large enough to maintain a credentialing program |
| Roster | The periodic file a delegated entity (or any group) sends the payer listing active providers and locations | Roster errors cause loading errors; reconcile it quarterly |
| Closed panel | The payer is not accepting new providers in a specialty or area | A credentialed provider can still be refused a contract; ask before the physician is hired |
| Locum tenens | A substitute physician billed under the absent physician's NPI with modifier Q6, for up to 60 continuous days under Medicare rules | A bridge for absences, not for a new hire awaiting enrollment |
Maintenance terms
Re-credentialing. Payers re-verify participating providers on a cycle, typically every three years under NCQA standards (36 months). The provider receives a request, usually satisfied through CAQH if the attestation is current.
Term (termination) and term date. The date a provider's participation ends, whether by leaving the group, by the payer's action, or by failing re-credentialing. Claims after the term date deny. Practices should term departed providers promptly, and just as important, confirm the payer did not term the wrong one.
Directory attestation. Separate from CAQH, several payers and the federal No Surprises Act rules require providers to confirm directory information (address, phone, accepting new patients) at intervals. Failing to attest can lead to removal from the directory, which some plans treat as a network status change.
Where practices get lost
Three confusions account for most of the calls we get. The first is credentialed versus loaded: the approval letter arrives, claims go out, and they deny with CO-B7 (provider not certified or eligible for this service) or an out-of-network adjudication because the load has not happened. Ask for the effective date and the load confirmation, in writing, before the first claim.
The second is the belief that Medicare's 30-day retroactive window applies to commercial plans. It does not. A physician seeing Blue Cross patients for six weeks before the Blue Cross effective date has produced six weeks of claims the practice will most likely absorb or bill as out-of-network, depending on the plan and state law.
The third is the CAQH attestation. It lapses every 120 days, no one at the practice sees the reminder because it goes to the physician's personal email, and the payer's file silently stalls. The fix is boring: a shared calendar entry for every provider, and a practice-controlled email on the CAQH account. If keeping all of this straight for a growing group is more than the office can carry, that is what our credentialing and provider enrollment team does every day.
Questions we hear
How long does credentialing take?
Medicare through PECOS often takes 30 to 60 days when the application is clean; commercial plans commonly quote 90 to 120 days and sometimes take longer. Hospital privileging runs in parallel on its own schedule. The realistic plan for a new hire is to start applications 120 to 150 days before the start date.
Can a new physician see patients while enrollment is pending?
For Medicare, yes, with the 30-day retroactive limit in mind. For commercial plans, generally not in-network. Some practices schedule the new physician on self-pay, Medicare and already-contracted plans first, and add commercial payers as effective dates arrive.
What is the difference between credentialing and privileging?
Credentialing verifies qualifications. Privileging is a hospital's or surgery center's grant of permission to perform specific procedures there. Payers credential; facilities credential and privilege.
What to do this week
- Pull the NPPES record for every provider and confirm taxonomy, practice address and license data match what you are submitting to payers.
- Log in to CAQH for each provider and record the next attestation date on a shared calendar.
- Check PECOS revalidation due dates for every enrolled provider and the group.
- For each payer, write down the effective date and load confirmation for the newest provider; chase any that are missing.
- Term any departed provider's reassignment (CMS-855R) and commercial participation that is still open.
