Form W-9: Request for Taxpayer Identification Number

Who Files Form W-9

US persons (individuals, sole proprietors, partnerships, LLCs, corporations) provide a W-9 to businesses that will issue them a Form 1099 (typically 1099-NEC for non-employee compensation of $600+ in a year). Foreign payees use Form W-8 series instead.

What Form W-9 Reports

The W-9 certifies the taxpayer's legal name, mailing address, TIN (SSN or EIN), tax classification (individual / sole proprietor / C-Corp / S-Corp / partnership / LLC), and exemption status. The W-9 is not filed with the IRS: it is retained by the requesting party for use when issuing the 1099.

Key Deadlines

• No fixed deadline: provide upon request before the first payment
• Update W-9 immediately after a name change, EIN change, or entity restructure

Common Mistakes

• Providing the wrong TIN type (SSN instead of EIN, or vice versa) for the entity
• Marking the wrong tax classification (single-member LLC versus disregarded entity rules)
• Failing to update a W-9 after S-Corp election or LLC restructure
• Sharing W-9 over insecure email: it contains a full SSN or EIN

Best Practices

• Always send the W-9 securely, never by unencrypted email. Encrypted client portal, password-protected PDF, or fax are acceptable. The W-9 contains a full SSN or EIN.
• Update the W-9 immediately after S-Corp election, EIN change, or legal name change. Outdated W-9s cause 1099-NEC issuance to the wrong entity.
• For single-member LLCs, mark the box matching the entity disregarded status (or its corporate election). The wrong box can trigger backup withholding.
• If you are exempt from backup withholding, complete Part II so the requester does not withhold 24 percent from your payments.
• Retain a copy of every W-9 you send for at least four years for audit support.

Source: Official Form W-9 information at IRS.gov