How Do You Bill While Insurance Credentialing Is Pending for a New Provider or New Owner?

What Medicare allows for billing back after enrollment

Under 42 CFR 424.520(d), the effective date for physicians, nonphysician practitioners and their groups is the later of the filing date of an application “that was subsequently approved” and the date the provider “first began furnishing services at a new practice location.” Under 424.521(a), they may bill for services up to 30 days before that date “if circumstances precluded enrollment in advance,” or 90 days when a Presidentially-declared disaster precluded it, provided all program requirements, including state licensure, were met.

CMS’s Program Integrity Manual gives the example. A physician starts at an office March 1, files May 1 and is approved June 1. The effective date is May 1, the retrospective billing date is April 1, and “claims submitted for services provided before April 1 will not be paid.” By the same rule, an application filed February 15 would have made March 1 the effective date.

A provider joining a group also reassigns benefits to it, now in Section 4(F) of the CMS-855I, since CMS discontinued the CMS-855R. Under 42 CFR 424.522, the reassignment follows the same later-of rule and 30-day look-back. While approval is pending, the one-year filing limit in 42 CFR 424.44 keeps running from each date of service.

A missed deadline pushes the date later. Under 42 CFR 424.525, an application can be rejected when requested information is not furnished “within 30 calendar days”; a rejection cannot be appealed, and the new application’s filing date becomes the one that counts. CMS’s PECOS notice says an application returned for corrections is rejected if the corrections do not arrive within 30 days. In order:

• The CMS-855I with Section 4(F), filed in PECOS before the first day of work.
• Every contractor request answered inside 30 days, both dates logged.
• The approval letter’s dates entered in the tracker the day it arrives, and held claims released.
• Each Medicare Advantage plan credentialed separately: under 42 CFR 422.204, a plan’s own initial credentialing covers, among other items, “eligibility for payment under Medicare.”

Is credentialing taking months normal?

For an online Medicare application, more than 85 days of processing is outside the standards CMS sets for its contractors, not counting the pauses the manual allows, such as waiting on fingerprint results or a question referred to CMS. Section 10.5 of the Program Integrity Manual sets 95 percent within 15 calendar days and all within 50 when no site visit, request for information or fingerprinting is needed, and 95 percent within 50 days and all within 85 when one is. Past that, check PECOS for an unanswered request first.

For commercial plans, months can be within the rules. This guide found no federal deadline for a commercial plan to finish credentialing; some states set one. New York’s Insurance Law §4803 gives an insurer sixty days from a completed application to decide, or to say a third party’s documents are missing, so get the plan’s written confirmation that the file is complete.

Credentialing is also only the first half: UnitedHealthcare’s guide says it gives notice of an initial credentialing decision within 30 calendar days of its committee’s decision, and the contract follows. For Medicaid, 42 CFR 438.602(b) has the state enroll every managed care network provider and lets a plan contract for up to 120 days while that is pending, so the state application goes in the same week as the plans’. The practice’s own dates tell slow from stuck: sent, confirmed complete, each request answered, approved, effective.

Why claims sit unpaid after a practice is bought or the tax ID changes

A payer pays under a tax ID it has on file, into the bank account on file for that tax ID. A sale or a new entity can change both, and until each payer loads the new record, claims under the new tax ID can be delayed or denied.

For Medicare, 42 CFR 424.516(d) requires a group to report a change of ownership within 30 days, and 424.550(c) says that, generally, a change of ownership that also changes the tax ID requires “a new enrollment application from the new owner.” For a group, that is a new CMS-855B, each provider reassigning benefits to it, and the CMS-588 for electronic payment that 42 CFR 424.510 requires. The later-of rule sets the new effective date, so each day between closing and filing is a day the 30-day look-back has to cover, and 424.550(a) bars letting another entity use a Medicare billing number.

Commercial payers each have their own steps. UnitedHealthcare’s 2026 guide lists the tax ID among the changes to report at least 30 calendar days before they take effect, warns that missing the notice can delay or deny claims payment, and says its Optum Pay direct deposit enrollment asks for a voided check and the practice’s IRS Form W-9. Ask every payer, in writing:

• Is this an update to the existing agreement, or a new agreement with new credentialing for every provider?
• What must be sent (a W-9, ownership papers, applications), how far ahead, and where?
• What effective date will the payer put in writing for the new tax ID?
• Does electronic payment and remittance enrollment need to be redone for the new tax ID and account?
• Which tax ID do claims for earlier dates of service carry?

The purchase agreement and the practice’s attorney answer the rest: who collects for visits before closing, and whose account receives payments sent under the seller’s tax ID afterward. For a dental practice that changes hands, the same questions go to each dental plan, and claims waiting on the answers belong on the dental insurance aging report with a note.

The enrollment tracker: one row per provider, payer and tax ID

The tracker works like a prior authorization log: dates, a reference number, an owner and a weekly look-ahead. One row per provider, per payer, per tax ID:

• Provider, individual NPI, and the group, tax ID and location the provider bills under.
• Payer and product, each listed separately: traditional Medicare, each Medicare Advantage plan, state Medicaid, each Medicaid managed care plan, each commercial plan.
• Request type: new provider, addition to a group contract, tax ID or ownership change, new location, recredentialing.
• Date sent, channel (PECOS, the CAQH Provider Data Portal, a payer portal, paper) and reference number.
• Date the payer confirmed the file complete, in writing.
• Each request for information: date received, date due, date answered.
• Decision date and the effective date as the payer wrote it; for Medicare, the retrospective billing date too.
• Electronic payment and remittance enrollment for that tax ID.
• Next action, owner and follow-up date.
• Renewals: Medicare revalidation, recredentialing (at least every 3 years for Medicare Advantage under 42 CFR 422.204), license, DEA registration, malpractice coverage.

Every week, one person reads it against the new provider’s next four weeks of schedule, by payer, and against the hold list: claims waiting on an enrollment, by payer, with count, dollars, oldest date of service and days left to that payer’s filing limit. Any B7, 242 or N570 on a remittance joins the agenda. Illustrative example: a hypothetical four-physician practice hires a nurse practitioner who starts June 2, with her Medicare application in PECOS May 12, so once approved her effective date can be June 2. Two commercial plans make her active in July and August; a third has not confirmed her file complete by September, and the hold list shows 38 of her visits for it, about $4,600, the oldest from June 4. That plan gets a follow-up call every Monday until a date is in writing.

How to schedule patients in the gap without losing the revenue

The cheapest held claim is the one never booked into a gap. Scheduling decides how much waits:

• Give the front desk each new provider’s status by payer (active, pending with a date, or pending without one) and book by it.
• Book the new provider first with patients of plans where the provider is active, and route patients of pending plans to clinicians already active with them.
• For traditional Medicare, file before the first day of work, so the start date can be the effective date and Medicare patients can be booked from day one, with their claims held until approval.
• In New York, Insurance Law §4803 covers a professional who is newly licensed, or who recently moved from another state and has not practiced in New York, and joins a group whose professionals all participate with an insurer. If a completed application is undecided after sixty days, that professional is provisionally credentialed, once the group tells the insurer in writing that, on a denial, it will refund in-network payments above the out-of-network benefit and bill the patient no more than the in-network cost share.
• In Texas, Insurance Code §1452.104 has a managed care plan treat a physician joining an established medical group with a current contract as participating, for payment only, once the physician submits the required information; if credentialing fails, §1452.106 lets the plan recover the difference between in-network and out-of-network payments, and §1452.107 bars billing the patient for what the plan does not pay.
• Self-pay visits, only after checking the group’s plan contracts. Under 45 CFR 149.610, uninsured or self-pay patients must be told a good faith estimate is available and receive one within 1 business day of scheduling a service 3 to 9 business days out, or within 3 business days for one 10 or more business days out. For a Medicare or Medicaid patient, ask counsel before charging for a visit the program will not pay.
• Each held claim carries a payer, a date of service, that payer’s filing limit and a release date. The one closest to its filing limit sets the deadline.

One person owns the tracker and the hold list, with the authority to move a new provider’s schedule. If billing is outsourced, the hold list belongs in the billing company’s monthly reports, but the enrollment dates and the schedule still live at the practice.

When the tracker is enough, and where the Review fits

A practice that files Medicare before the start date and has every payer’s effective date in writing before the first booked visit needs nothing more than the tracker. If a payer is past a deadline in its own manual or a state statute, the next call is the practice’s attorney or the state insurance department, not a consultant.

An outside look earns its fee when nobody can say how many claims wait on an enrollment, what they are worth or when the oldest reaches its filing limit, or when B7 and N570 keep arriving without anyone tracing them to the schedule. The Revenue Review takes two weeks; its first pass reads aggregate exports — held claims by payer, remittance codes, the schedule by provider and payer, any tracker — not patient names, and it ends with a written report that prices each finding and a 90-day plan. It does not file enrollment applications, credential providers or give legal advice. A free 20-minute call is enough to tell whether it fits.