How to fax a W-9 and ownership change to insurers for credentialing

A practice that changes its tax ID or ownership sends each payer a new W-9 with the new name and TIN, plus whatever change form that payer requires. Medicare wants a physician practice's change of ownership reported within 30 days, and a new TIN means a new Medicare enrollment application rather than a change request.

How do you send a W-9 and an ownership change to insurers?

A W-9 and an ownership change go to each payer by the route that payer's own form or provider guide names, with a new W-9 whenever the name or TIN changes and the payer's change form beside it. Rules vary by payer and by state, and the payer's own form and fax number govern. UnitedHealthcare's 2026 administrative guide wants changes, the TIN among them, at least 30 calendar days before they take effect and warns that a late notice can delay or deny claims payment.

Evernorth Behavioral Health's September 2026 guidelines for psychiatrists, psychologists and master's-level therapists ask for notice 90 days before a change to the TIN, a service location or a billing address. Humana's 2026 provider manual says a change in practice name, legal entity or TIN might require an amendment, an assignment or a new agreement, and it asks for changes at least 30 days ahead. Public programs run their own clocks: 42 CFR 455.104 gives Medicaid ownership disclosures 35 days after a change in ownership, and a Veterans Care Agreement needs changes that affect provider status reported within 10 business days.

The table lists each document or update, who needs it and the clock it runs on.

When does a payer ask for a new W-9?

A payer needs a new W-9 whenever the name or TIN on the account changes, because Form W-9 says the payee must furnish a new form in that case. The form goes to the requester and is never sent to the IRS. The IRS's page on when to get a new EIN says a business needs one, in general, when its ownership or structure changes, and does not need one for a new business name or address alone.

On Form W-9, a single-member LLC disregarded as separate from its owner enters the owner's SSN, or the owner's EIN if there is one, while an LLC classified as a corporation or partnership enters its own EIN. A payee that fails to furnish a correct TIN faces a $50 penalty for each failure, unless the failure is due to reasonable cause and not willful neglect. The IRS's Topic 307 adds 24% backup withholding when a payee does not give its TIN in the required manner.

Aetna's W-9 and 1099 FAQ puts a TIN that does not match IRS records on its B Notice file: a first B Notice requires a W-9, while a second one, for a TIN flagged twice within three years, requires IRS Letter 147C for an EIN, because a W-9 will not do. When a professional corporation, professional association or LLC enrolls in Medicare, or a sole proprietor enrolls with an EIN, the CMS-855B asks for written IRS confirmation of the TIN and legal business name, such as IRS form CP-575.

What does Medicare need, and how fast?

Medicare needs a change of ownership, any adverse legal action and a change, addition or deletion of a practice location reported within 30 days, and every other enrollment change within 90 days, under 42 CFR 424.516. That 30-day rule covers physicians, nonphysician practitioners and their organizations. CMS's provider enrollment booklet, MLN9658742, describes the same group to practice organizations as a change of ownership or control, including a new authorized official, delegated official or managing employee, a practice location change, and final adverse legal actions.

The CMS-855B says an enrolled supplier with a new tax identification number must complete a new application, and 42 CFR 424.550 says a change of ownership that also changes the TIN generally requires a new application from the new owner. The booklet says PECOS cannot change a TIN or an existing business structure, so those changes go on the paper CMS-855.

Groups and other organizational suppliers, except DMEPOS suppliers, use the CMS-855B, and individual practitioners, including sole proprietors and sole owners of a corporation, use the CMS-855I. CMS's bulletin on the CMS-855I says Medicare merged the CMS-855R reassignment form into it, and the CMS-855B (12/2025) now also carries reassignment changes between a group and a practitioner.

Certified providers file earlier. Under 42 CFR 424.550(b), a provider changing ownership under 42 CFR part 489, such as a hospital, files before the change is complete, and 42 CFR 424.526 lets CMS return a CMS-855A or CMS-855B change of ownership application filed more than 90 days before the anticipated sale.

42 CFR 424.515 requires revalidation every 5 years, other than for DMEPOS suppliers, and an answer within 60 calendar days of CMS's notice; CMS's revalidation page posts due dates seven months in advance. CMS's participation page sets the yearly participation decision from mid-November through December 31.

How do CAQH and NPPES updates fit in?

CAQH (now DataSpring, powered by CAQH) and NPPES each hold a record that has to change with the practice, on its own clock: the CAQH profile is re-attested every 120 days, 180 in Illinois, and NPPES changes are due within 30 days. CAQH's Provider Data Portal user guide also requires signed supporting documents within 120 days of the signature date. It marks a document missing a date or a signature as not compliant, and it expects one Tax ID for each practice location record. DataSpring's Practitioner Quick Reference Guide, version 4.0, repeats the 120-day cycle and says the provider gets a notification to re-attest.

NPPES runs under 45 CFR 162.410, which gives a covered provider 30 days to report a change in its required data elements. CMS's PECOS fact sheet says the legal business name and the individual provider's name must match between NPPES and PECOS, and that an NPPES update does not change PECOS. Other offices look up a practice's fax number in the same record, as how to find a doctor's fax number in the NPI Registry shows.

Medicare Advantage plans recredential on their own cycle: at least every 3 years under 42 CFR 422.204.

Can you fax credentialing paperwork, or does it go through a portal?

Credentialing paperwork goes by fax where the requester accepts it, as the IRS allows for a W-9, and through a portal or the mail where the requester requires it, as CAQH, Novitas and CGS do. The IRS's Form W-9 instructions let requesters set up a system for payees to submit Forms W-9 electronically, including by fax, and Aetna takes W-9 name and address changes by email or fax to its provider tax team.

CAQH's 2023 user guide says the Provider Data Portal does not support faxing of supporting documents. Its 2024 document upload guide for Washington State providers takes a PDF, JPEG, JPG or TIF file under 12MB, or up to 10 documents emailed to a CAQH documents mailbox, with 2 to 3 business days for review. DataSpring's quick reference lists W-9 forms among the documents uploaded directly.

Novitas Solutions' enrollment FAQ says a paper CMS-855 cannot be faxed or emailed and goes by U.S. mail, FEDEX or another direct mailing with a handwritten or eligible digital signature. CGS's Part B page on application delays says a faxed CMS-855I cannot be accepted, and 42 CFR 424.525 lets CMS reject an application sent by fax or email when the provider was not otherwise permitted to.

One page does travel by fax. The Program Integrity Manual, chapter 10, lets a supplier answer a contractor's request for a certification statement on a paper CMS-855B by scanned email, fax or mail, with only the signature page required. Noridian's fax guidelines list a Provider Enrollment department and ask for a cover sheet with the total pages, the department name, the provider's name and contact information, and one transmission per request.

What should you do with a payer's contract amendment?

A payer's contract amendment is read against the contract and the state's law, because some states set how much notice an amendment needs and what happens when the provider stays silent. Texas Insurance Code section 1301.0642, added in 2023, allows an adverse material change to a preferred provider contract during its term only by mutual agreement, voids a clause letting the insurer change the contract alone, and holds the change until the 120th day after the provider agrees in writing.

Ohio Revised Code section 3963.04 requires a material amendment to be delivered in writing with notice no later than 90 days before it takes effect. The provider may object in writing within 15 days, and without an objection the amendment takes effect as the notice says. For Medicare Advantage, 42 CFR 422.202 requires at least 60 days' written notice from either side before a contract ends without cause.

What mistakes stall credentialing?

Credentialing stalls on names and numbers that do not match, signatures that are too old, the wrong route and missed notice windows, each named in a payer's or regulator's own instructions:

• A legal business name, TIN or NPI that differs between PECOS and NPPES; the CMS-855B requires them to match exactly in both.
• An application signed more than 120 days before the Medicare contractor receives it, a ground for rejection under 42 CFR 424.525(a)(1)(iv).
• A CMS-855 sent by fax or email where the contractor takes mail only.
• A change sent to Noridian on business letterhead; its Jurisdiction E Part B page requires the CMS-855 form, and a legal business name change also needs a new EFT form and an NPPES update for the Type 2 NPI.
• A development letter left unanswered; the 30-day clock starts when the contractor mails, faxes or emails it, and a follow-up does not restart it.
• A CAQH document missing a date or signature, or a practice location added twice with the same address and Tax ID.
• A W-9 whose name and TIN do not match IRS records, which lands the TIN on the B Notice file.
• A payer notice sent later than the payer's window allows, such as UnitedHealthcare's 30 calendar days before the change or Evernorth's 90 days.

How do you send credentialing paperwork from a HIPAA fax account?

Fax Pigeon's e-signatures put the practice's signature on a W-9 or a payer's change form before it goes out from the browser or from email, as how to sign a fax and send it back shows. Delivery proof comes with each delivered fax, to keep with the copy sent to that payer. A development letter or payer follow-up that comes back by fax goes to the shared inbox and can be assigned to the person running the change. The BAA signed at signup covers every plan, so the same account can send patient records too.

* Official sources (the eCFR, CMS, the IRS, CAQH, VA) were read on October 19, 2026. Fax Pigeon prices and plan terms as of October 20, 2026.