On Form W-9, “C Corporation” is the federal tax classification you check when your business is a corporation taxed under Subchapter C of the Internal Revenue Code, meaning it files its own return and pays tax at the entity level. Marking the C Corporation box on Line 3a tells the requester how your business is taxed, which controls whether they must withhold from your payments and whether they need to issue you a 1099 at year-end.
What the C Corporation Box Signals
A C corporation is a separate taxpayer from its owners. The corporation files Form 1120 and pays federal income tax on its profits at the entity level.1Internal Revenue Service. About Form 1120, U.S. Corporation Income Tax Return When you check the C Corporation box, the requester learns two things at once: your business is a corporation (not a pass-through), and it has not elected S corporation treatment.
That distinction matters to the payer because corporations are generally exempt from backup withholding and from most 1099 reporting. The W-9 is the payer’s documentation that the exemption applies.
Are You Actually a C Corporation?
If your business went through a formal state incorporation and you never filed IRS Form 2553 to elect S corporation status, your entity is a C corporation by default.2Internal Revenue Service. Filing Requirements for Filing Status Change An S election only takes effect once the IRS accepts it and sends an acknowledgment letter. No letter, no S election.
The fastest self-check is your last federal return. Form 1120 means C corporation. Form 1120-S means S corporation, and you should check the “S Corporation” box on the W-9 instead.
A few situations trip people up:
- LLC that elected corporate tax treatment on Form 8832: check the “Limited liability company” box on Line 3a and enter “C” in the tax classification field. Do not check the standalone “C Corporation” box, even though your LLC files Form 1120.3Internal Revenue Service. Form W-9 (Rev. March 2024)4Internal Revenue Service. LLC Filing as a Corporation or Partnership
- Sole proprietor: the business and the owner are the same taxpayer, so check “Individual/sole proprietor,” never C Corporation.
- Partnership: income and losses pass through to the partners, so check “Partnership.”
Filling Out the Form as a C Corporation
The current W-9 is one page, but each field has to match what the IRS already has on file for your EIN. A mismatch can delay payments or trigger a penalty.
Line 1: Legal Name
Enter the corporation’s legal name exactly as it appears on your Form 1120 and on the IRS records for your Employer Identification Number.3Internal Revenue Service. Form W-9 (Rev. March 2024) When your corporation first received its EIN, the IRS issued Notice CP 575 showing the exact legal name and number. If you no longer have that notice, you can verify the information by calling the IRS Business and Specialty Tax Line at 800-829-4933.
Line 2: Trade or DBA Name
If the corporation operates under a “doing business as” name, put it on Line 2. Putting a DBA on Line 1 causes a name/TIN mismatch with IRS records.
Line 3a: Federal Tax Classification
Check “C Corporation.” If your entity is an LLC that elected C corporation treatment, check the “Limited liability company” box and write “C” in the classification field instead.3Internal Revenue Service. Form W-9 (Rev. March 2024)
Line 4: Exempt Payee Code
Corporations correspond to exempt payee code “5” on Form W-9. Enter 5 in the exempt payee code field to document the corporation’s exemption from backup withholding on common payment types such as interest, dividends, and broker transactions.3Internal Revenue Service. Form W-9 (Rev. March 2024)
The FATCA reporting code on the same line generally does not apply to standard domestic C corporations. FATCA reporting targets foreign financial institutions and non-financial foreign entities. If your corporation is not publicly traded and does not fall into one of the specific categories listed on the form, leave the FATCA field blank or write “N/A.”
Lines 5 and 6: Address
Enter the address where the requester should send information returns and other tax documents. This is usually your principal business address or the address of your registered agent.3Internal Revenue Service. Form W-9 (Rev. March 2024)
Part I: Employer Identification Number
Enter the corporation’s nine-digit EIN. A C corporation always uses its EIN, never a Social Security Number, and an LLC electing corporate treatment uses the entity’s EIN rather than the owner’s SSN.3Internal Revenue Service. Form W-9 (Rev. March 2024) Providing an incorrect or missing TIN when required can carry a $50 penalty per failure, up to $100,000 in a calendar year.5Office of the Law Revision Counsel. 26 USC 6723 – Failure to Comply With Other Information Reporting Requirements
Part II: Certification and Signature
Someone authorized to act for the corporation signs and dates the form under penalties of perjury, certifying that the TIN is correct, that the corporation is not subject to backup withholding, and that the entity is a U.S. person.3Internal Revenue Service. Form W-9 (Rev. March 2024) Requesters can accept electronic signatures, including faxed submissions, as long as the electronic signature carries the same perjury certification as the paper form.6Internal Revenue Service. Instructions for the Requester of Form W-9
Backup Withholding When the W-9 Is Missing or Wrong
If your corporation does not deliver a correct W-9, the payer may have to withhold 24 percent of each reportable payment and remit it to the IRS as backup withholding.7Internal Revenue Service. Instructions for the Requester of Form W-9 (Rev. January 2026) Backup withholding applies when a payee fails to furnish a TIN, provides an incorrect TIN, or has been notified by the IRS of underreported income.8Office of the Law Revision Counsel. 26 USC 3406 – Backup Withholding
Corporate status alone is not enough to prevent this. Without a W-9 on file, the payer has no documentation of the exemption and will often withhold to protect itself. Sending the completed form up front is what unlocks the exemption in practice.
Whether You’ll Still Get a 1099
For most payment types, checking C Corporation means the payer does not issue you a Form 1099-NEC or 1099-MISC. Payments to C or S corporations are generally not reportable on those forms.9Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC
Several categories are carved out of that general rule, and payments to your C corporation will still be reported when they fall into one of them:
- Attorney fees for legal services, reported on Form 1099-NEC, Box 1.
- Medical and health care payments to corporations, including professional corporations, reported on Form 1099-MISC, Box 6.
- Gross proceeds paid to an attorney’s corporation in connection with a settlement, reported on Form 1099-MISC, Box 10.
- Cash payments for fish purchased for resale, reported on Form 1099-MISC, Box 11.
- Payments by federal executive agencies for services, reported on Form 1099-NEC regardless of corporate status.9Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC
For every other type of payment, the W-9 you provide is what documents the payer’s decision not to send a 1099.
Foreign-Owned U.S. C Corporations
A U.S.-incorporated C corporation uses Form W-9 even if it is entirely owned by foreign shareholders, because the corporation itself is a U.S. entity. Form W-8BEN-E is reserved for foreign entities.3Internal Revenue Service. Form W-9 (Rev. March 2024) A separate obligation may apply on the income tax side: a C corporation with at least one foreign shareholder holding 25 percent or more of voting power or stock value must file Form 5472 with its annual return to report transactions with related foreign parties.10Internal Revenue Service. Instructions for Form 5472
Sending, Updating, and Keeping the Form
Form W-9 does not go to the IRS. You return it to the party that requested it, usually a client, bank, or financial institution. Because it contains your EIN, use a secure delivery method such as encrypted email or a protected document portal.
Furnish a new W-9 whenever the name or TIN on the account changes. That includes legal name changes, mergers, and conversions from C corporation to S corporation status.3Internal Revenue Service. Form W-9 (Rev. March 2024) Every requester with your old form on file needs the updated one.
Keep a copy of every W-9 you submit. The IRS generally advises retaining tax records for at least three years from the filing date, with longer retention in specific situations such as underreported income or bad-debt deductions.11Internal Revenue Service. How Long Should I Keep Records Consistent copies across client accounts also protect the corporation if a payer later claims it never received the form.