Form W-9 looks like the simplest tax form in the world. One page, eight lines, a signature, done. That impression is exactly why it is the form US companies handle most carelessly, and why we see backup withholding notices land in finance team inboxes 18 months after the fact.
This guide walks through Form W-9 from the requester’s perspective. We cover who provides the form, how to verify it, what the IRS TIN Matching Program does, the 24% backup withholding rate, and where to draw the line between W-9 and the W-8 series.
All claims are sourced directly from the IRS About Form W-9 page and the IRS Instructions for the Requester of Form W-9 (Rev. March 2024).
What Form W-9 Is
The full name of the form is “Request for Taxpayer Identification Number and Certification.” It serves a single purpose: a US person hands it to a requester so the requester has the recipient’s correct name, taxpayer identification number, and certain certifications needed to file information returns about payments made to that recipient.
The IRS About Form W-9 page captures the purpose: the form is used to provide your TIN to entities required to file information returns with the IRS, such as those reporting income payments, real estate transactions, mortgage interest, or debt cancellations.
The current revision is March 2024.
W-9 is not filed with the IRS. The contractor provides it to the company that pays them. The company keeps it on file and uses the information to prepare year-end 1099-NEC, 1099-MISC, 1099-K, 1099-INT, 1099-DIV, or similar forms.
When You Collect a W-9
You collect a W-9 from any US person you will be making reportable payments to. In the contractor context, that means every US contractor whose total payments for the year are expected to meet the Form 1099-NEC reporting threshold (which is $600 for 2025 and $2,000 for payments after December 31, 2025 under the One Big Beautiful Bill Act).
In practice, you collect a W-9 from every US contractor at onboarding regardless of expected payment volume. The marginal cost of collecting it is zero, and you avoid the situation where a $500 engagement balloons to $5,000 over the year and you scramble to backfill the form before the January 31 filing deadline.
For non-US contractors, you collect Form W-8BEN instead. We cover that in our Form W-8BEN Filing Guide.
Who Is a US Person
The IRS Instructions for the Requester of Form W-9 define a US person as:
- A US citizen
- A US resident alien (including someone with a green card or who meets the substantial presence test under IRS Publication 519)
- A partnership, corporation, company, or association created or organized in the United States or under US law
- An estate (other than a foreign estate)
- A domestic trust
A few edge cases worth flagging:
- A US citizen living abroad permanently is still a US person and uses W-9, not W-8BEN.
- A green card holder is a US person regardless of where they currently live or work.
- A US LLC formed in Delaware is a US person, even if all its owners are foreign.
- A non-US individual who has an ITIN is not automatically a US person. The ITIN is just a taxpayer identification number. Status as a US person depends on citizenship or substantial presence, not on having a TIN.
If the contractor checks any of the US person boxes, W-9 is the right form. If not, route them to the appropriate W-8 series form.
Walking Through the Form
Form W-9 has eight fields plus a signature block. Each one matters.
Line 1: Name
The name on Line 1 must match the IRS records for the TIN provided on the form. For an individual, this is the name on their Social Security card. For a single-member LLC owned by an individual, this is the owner’s name, not the LLC name. For a multi-member LLC, partnership, or corporation, this is the entity’s legal name.
The IRS TIN Matching Program uses Line 1 + the TIN to validate the record. Mismatches here are the leading cause of CP2100 notices.
Line 2: Business name or disregarded entity name
This is the “doing business as” name or the LLC name if it differs from the owner’s name on Line 1. It is the cosmetic name, not the legal one.
Line 3: Federal tax classification
The contractor checks one box: Individual/sole proprietor or single-member LLC, C Corporation, S Corporation, Partnership, Trust/estate, Limited liability company (with a separate tax classification entry), or Other.
This drives whether 1099-NEC reporting is required. Payments to corporations are generally exempt from 1099-NEC reporting under the IRS Instructions for Forms 1099-MISC and 1099-NEC, with the major exception of payments for legal services, which are reportable regardless of the attorney’s entity type.
Line 4: Exemptions
This line is rarely used by contractors. It is for payees exempt from backup withholding or FATCA reporting. The categories are listed in the IRS Instructions for the Requester of Form W-9 and include items like tax-exempt organizations, government entities, and certain financial institutions.
Lines 5 and 6: Address
The contractor’s address, used as the mailing address for any 1099 issued.
Part I: Taxpayer Identification Number
The TIN is either a Social Security Number for individuals and sole proprietors, or an Employer Identification Number for entities. The format is XXX-XX-XXXX for SSN and XX-XXXXXXX for EIN.
Common errors: providing the EIN of a single-member LLC when the owner is an individual (the IRS expects the owner’s SSN on Line 1 + TIN), or providing an ITIN when an SSN exists.
Part II: Certification
The contractor certifies under penalty of perjury that:
- The TIN is correct (or that they are waiting for one to be issued).
- They are not subject to backup withholding because they have not been notified that they are subject to backup withholding for failure to report interest and dividends, or the IRS has notified them that they are no longer subject.
- They are a US person (including a US resident alien).
- The FATCA codes entered on the form (if any) are correct.
The contractor signs and dates. An unsigned W-9 is not a valid form.
The IRS TIN Matching Program
The single best tool for catching W-9 errors before they become penalties is the IRS TIN Matching Program.
It is a free service available through IRS e-services to authorized payers. You submit a list of name and TIN combinations and the system returns either a match indicator or one of several mismatch codes.
The two modes are:
- Interactive TIN Matching: up to 25 name and TIN combinations at a time, with results returned in real time.
- Bulk TIN Matching: up to 100,000 combinations per file, with results returned within 24 hours.
A typical onboarding workflow runs TIN matching as the W-9 is submitted. If the system returns a no-match, the contractor is asked to correct the form before the first payment is released.
The benefit of running TIN matching at onboarding is real money. The penalty for filing a 1099 with an incorrect TIN is set in IRC section 6721. It is small per form, but it scales fast across a contractor base of hundreds.
Backup Withholding: The 24% Rule
Backup withholding is a 24% withholding on certain reportable payments. The IRS Instructions for the Requester of Form W-9 confirm “the backup withholding rate is 24% for reportable payments.”
You are required to begin backup withholding in any of these situations:
- The payee failed to furnish a TIN.
- The IRS notifies you that the TIN furnished is incorrect.
- The IRS notifies you that the payee has been underreporting interest or dividends.
- The payee fails to certify on Form W-9 that they are not subject to backup withholding.
The 24% is collected on the gross payment and reported on Form 945 (the annual return of withheld federal income tax). The contractor receives credit for the withholding when they file their personal return.
The most common backup withholding trigger in the contractor context is #1: the contractor never returned a signed W-9. Until you have one, the next 1099-reportable payment must have 24% withheld.
Distinguishing W-9 from W-8
The single most useful clarification: W-9 and W-8 are not alternatives chosen by the contractor. The form is determined by the contractor’s tax status, not by their preference.
- W-9: US persons (including resident aliens and US entities)
- W-8BEN: Foreign individuals
- W-8BEN-E: Foreign entities
- W-8ECI: Foreign persons whose income is effectively connected with a US trade or business
- W-8EXP: Foreign governments, foreign tax-exempt organizations
- W-8IMY: Foreign intermediaries, flow-through entities
A contractor who is unsure typically defaults to W-9 because it is the form they know. As the requester, you have the obligation to verify the form matches the contractor’s actual tax status. If a contractor with a Toronto address fills out a W-9 listing a Canadian address, you should ask whether they are a US citizen or US resident alien. If not, route them to W-8BEN.
Our Form 1099-NEC vs W-8BEN comparison walks through the decision tree in more detail.
Retention
Form W-9 is not filed with the IRS, but you retain it as part of your records to support the information returns you file. The IRS Instructions for the Requester of Form W-9 do not specify a retention period for W-9, but the statute of limitations for related information return penalties under IRC section 6721 is generally three years from the date of filing.
Most companies retain W-9 indefinitely in their contractor record system. The marginal cost of storage is zero, and an old W-9 is the only documentary defense if the IRS later questions a 1099 you filed.
Common Mistakes
Three patterns we see repeatedly:
Skipping the form for “trusted” contractors. A founder hires a former colleague as a contractor and skips the W-9 because it feels awkward. Twelve months later, the contractor has received $30,000 and the company has no W-9 on file. The penalty for not having the TIN is backup withholding of 24% on every payment after the first reportable threshold. The fix is to collect the W-9 now and remit any backup withholding that should have been collected.
Using a stale W-9 after the contractor’s status changed. The contractor changes from sole proprietor to single-member LLC. The W-9 on file still lists their old TIN structure. The 1099-NEC issued at year-end uses outdated information and the IRS issues a CP2100 notice.
Treating a non-US contractor’s ITIN as US person status. A non-US contractor has an ITIN from a prior US engagement and submits a W-9 listing the ITIN. ITIN does not equal US person status. The form is invalid for them and the correct form is W-8BEN.
What a Modern Contract Management System Should Do
Manual W-9 collection works for the first five or ten contractors. Past that, the operational cost of chasing forms, running TIN matches, validating entity classifications, and producing year-end 1099s overwhelms a finance team.
A modern contract management platform handles all of this as part of contractor onboarding:
- Routes US contractors to W-9 and non-US contractors to W-8BEN
- Validates entity classification against the contract counterparty
- Runs IRS TIN Matching automatically
- Stores the form in structured fields, not as a PDF blob
- Generates year-end 1099-NEC from the same data
- Applies backup withholding automatically when a W-9 is missing or invalid
We cover the broader product positioning in our Contract Management vs Contractor of Record post.
The Operational Summary
Form W-9 is the gate every reportable payment to a US person passes through. Three rules cover 95% of the operational complexity:
- Collect at onboarding, not at year-end.
- Run IRS TIN Matching before the first payment.
- Refresh the form when the contractor’s name, TIN, or entity classification changes.
If any one of those three is missing, you are exposed. If all three are in place, the W-9 workflow runs on autopilot and 1099-NEC issuance becomes a January formality rather than a January fire drill.
If you want the W-9 and 1099-NEC workflow handled as part of contract onboarding, take a look at Omnivoo’s Contract Management product. Our pricing page covers the per-contract fee with payment processing at cost.