W-9 for a Therapy LLC: Which Name and Tax ID?

Last reviewed: October 7, 2026.

For a single-member LLC that is disregarded for federal income tax, the W-9 lists the owner’s name on line 1, the LLC’s name on line 2, checks “Individual/sole proprietor” on line 3a, and gives a TIN that belongs to the line 1 name. If the LLC has elected to be taxed as a corporation, it follows different instructions. Payers then check that name and TIN against how the IRS actually has the EIN registered, which is where most W-9 problems surface.

This is general information, not tax advice. Have the practice’s accountant confirm the classification before signing.

Filling it out line by line

The current Form W-9 instructions for a disregarded entity:

1. Line 1: the owner’s name. The line 1 owner must not itself be a disregarded entity.

2. Line 2: the LLC’s business name.

3. Line 3a: the owner’s classification, which for an individual owner is Individual/sole proprietor, not the LLC box.

4. Part I: a TIN that matches line 1. The IRS single-member LLC guidance says an individual-owned disregarded LLC uses the owner’s SSN or EIN here. In the single-member practices we work with, the practice EIN is usually registered to the owner, so it pairs with line 1 and is what payers expect to see; the next section explains how to tell.

5. Part II: the signature and date. If your biller asks you to sign a W-9, check whether they prefilled the top; if not, the identifying lines and Part I need to be completed too.

An LLC never uses the standalone S corporation box; that box is for entities that are corporations under state law. An LLC that wants an entity-shaped W-9 checks the LLC box and enters its tax classification letter.

What payers compare it to: your EIN letter

Payer and Medicare reviewers often hold the W-9 up against the IRS EIN confirmation letter (CP-575) or a replacement letter (147C). For a single-member LLC, that comparison surprises people:

• The EIN letter names the owner, not the LLC. For a disregarded single-member LLC, the IRS often issues the EIN letter in the owner’s personal name with no business name on it. That is normal. A 147C restates the same registration, so ordering one will not make the LLC’s name appear.

• Send the letter and the W-9 together. If a reviewer questions why the names differ, the EIN letter and a W-9 with the owner on line 1 and the LLC on line 2 explain each other.

• An S-corp election may not show up. Some letters read like “LLC name / owner name SOLE MBR,” and the IRS registration may still say that after an S corporation election. Illinois Medicaid’s EIN certification, for example, matched the disregarded-style W-9 for an LLC in that situation, not one with the S corporation box checked. Changing the W-9 to look more “corporate” can hand the payer a name and TIN pair the IRS does not recognize.

Where payers push back

A correct W-9 still is not always enough. Patterns we have run into:

• Group enrollments that will not accept a disregarded entity. Illinois Medicaid declined to certify an EIN whose IRS letter said “SOLE MBR” for a group enrollment. Its options were a W-9 with the owner’s SSN (not usable for a group), changing the tax classification with the IRS, or a specific multi-document disregarded-entity packet. Changing classification is a tax decision for an accountant, not a paperwork fix.

• Medicare asks how you file. A Medicare reviewer may ask which return the business files (Schedule C, 1065, or 1120/1120-S) to decide how to set it up. In PECOS, selecting “disregarded entity” also adds a request for an IRS Form 8832 letter, which a default single-member LLC usually never filed.

• Name differences that are real. Commas and capitalization rarely matter. A missing word such as “PLLC” on the IRS letter when every other document includes it does.

• Extra verification. Some payers verify the W-9 against other documents. A recent UnitedHealthcare tax ID verification also asked for a utility-style bill showing the practice or owner at the address, plus written attestations.

The IRS instructions for W-9 requesters explain the owner and disregarded-entity distinction from the payer’s side, which helps frame a clarification. Do not switch classifications, substitute an unrelated EIN, or alter an IRS document to clear a portal warning, and send tax documents only through the payer’s secure route.

Related: why to bill under your PLLC or PC rather than your SSN, the practice name and DBA change checklist, and the insurance-payer EIN change guide.

Related Guides

• Lost Your CP 575? Get an IRS 147C Letter for Credentialing

Frequently Asked Questions

Why does my EIN letter show my name instead of my LLC?

For a single-member LLC treated as a disregarded entity, the IRS commonly registers the EIN to the owner. It is not an error, and a 147C will show the same thing.

Do I check the LLC box on line 3a?

Not for a disregarded single-member LLC owned by an individual. Line 3a describes the line 1 taxpayer, so you check Individual/sole proprietor. An LLC taxed as a corporation follows different instructions.

Do I just sign the W-9, or fill out the top too?

Both, unless your biller already filled in the name, classification, address, and TIN. A signature on a blank form does not give the payer anything to match.

Should I get a 147C to fix a name mismatch?

Only if the mismatch is about which EIN or legal name is correct. A 147C repeats the IRS registration, so it will not add the LLC name for a disregarded single-member LLC.

Sources

• IRS: Current Form W-9 and Instructions

• IRS: Single-Member Limited Liability Companies

• IRS: Instructions for the Requester of Form W-9