Companies need a W-9 from vendors because they cannot file year-end 1099s without the vendor’s legal name and taxpayer identification number, and without a valid W-9 on file they are required to withhold 24% of every payment and send it to the IRS. The form is the paperwork that makes accurate information reporting possible and shields the paying company from backup withholding and per-form penalties.
What the W-9 Actually Gives You
Form W-9 collects two things from a vendor: the correct taxpayer identification number (TIN) and a signed certification about the vendor’s tax status.1Internal Revenue Service. About Form W-9, Request for Taxpayer Identification Number and Certification The TIN is usually a Social Security Number for a sole proprietor, an Employer Identification Number for a business, or an Individual Taxpayer Identification Number.2Internal Revenue Service. Taxpayer Identification Numbers (TIN)
The vendor signs under penalty of perjury that the TIN is correct and that they are not currently subject to backup withholding.3Internal Revenue Service. Form W-9 (Rev. March 2024) Request for Taxpayer Identification Number and Certification For the paying company, that signed form is the due diligence record showing a good-faith effort to collect accurate vendor information. It also tells you, through the entity type checkbox, whether you have a 1099 obligation at all.
Feeding the 1099 at Year-End
Everything on the W-9 exists so the company can prepare Form 1099-NEC (nonemployee compensation) or Form 1099-MISC (rents, royalties, medical payments, other miscellaneous income) at year-end. The IRS matches the income a company says it paid against what the vendor reports on their own return. Mismatches generate notices.
For payments made in 2026 and later years, 1099-NEC and 1099-MISC filing is required once total payments to a single vendor reach $2,000 in a calendar year, up from the prior $600 threshold. The threshold will adjust for inflation starting in 2027.4Internal Revenue Service. 2026 Publication 1099 Royalties still trigger reporting at $10.
Without a TIN, you cannot complete the 1099. Without the 1099, you have two separate problems: backup withholding you should have applied along the way, and penalties for the missing return.
The 24% Backup Withholding Problem
If a vendor fails to provide a correct TIN, or the IRS notifies you that a TIN is wrong, or the vendor won’t certify that they aren’t subject to backup withholding, federal law requires the paying company to withhold 24% of the payment and send it to the IRS.5Internal Revenue Service. Backup Withholding6Internal Revenue Service. Topic No. 307, Backup Withholding The rate is set under 26 USC 3406.7Office of the Law Revision Counsel. 26 U.S. Code 3406 – Backup Withholding
In real numbers: a $5,000 invoice from a contractor with no valid W-9 means the company pays the contractor $3,800 and remits $1,200 to the IRS. Vendors hate this, and the friction shows up immediately. The company has no discretion here. Failing to withhold when required makes the company itself liable for the amount, plus interest and penalties. Collecting the W-9 before the first check clears the whole problem.
Penalties for Missing or Wrong 1099s
Separate from backup withholding, filing a 1099 late, incorrectly, or not at all carries per-form penalties under IRC sections 6721 and 6722. For returns due in 2026, the inflation-adjusted amounts are:8Internal Revenue Service. Information Return Penalties
- $60 per return if corrected within 30 days
- $130 per return if corrected after 30 days but by August 1
- $340 per return if filed after August 1 or not filed at all
- $680 per return for intentional disregard, with no maximum cap
These stack. Section 6721 penalizes the return filed with the IRS; section 6722 penalizes the copy furnished to the vendor. Miss both and the penalties double. A company paying dozens of unincorporated contractors without W-9s on file can accumulate real exposure quickly, and the intentional disregard tier has no annual cap.
Which Vendors Actually Need to Give You One
Not every payment triggers a 1099, so not every vendor strictly needs a W-9. But the categories are messy enough that most accounts payable teams collect from everyone at onboarding rather than guess. That instinct is sound: a $500 engagement can grow to $10,000 by Q3, and by then the vendor has changed addresses and stopped answering.
The Corporate Exemption
Payments to C corporations and S corporations are generally exempt from 1099 reporting for services.9Internal Revenue Service. Am I Required to File a Form 1099 or Other Information Return The W-9 entity checkbox is how you confirm that exemption applies. Two exceptions cut through it: payments to law firms and payments for medical or health care services must be reported on a 1099 even when the recipient is incorporated.10Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC (04/2025) So you still need a W-9 from your incorporated law firm and your incorporated medical practice.
Payments for Goods
Payments for physical goods and merchandise generally do not require 1099 reporting.4Internal Revenue Service. 2026 Publication 1099 A vendor that only sells you office supplies or inventory typically does not need to send a W-9.
Credit Card and Payment App Transactions
Payments made through credit cards, debit cards, or third-party networks like PayPal are reported by the payment settlement entity on Form 1099-K, not by the paying company on a 1099-NEC or 1099-MISC.11Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC If a contractor is paid exclusively by card, the reporting shifts to the processor. Many companies still collect the W-9 anyway because payment methods can change mid-year.
Foreign Vendors
The W-9 is for U.S. persons only. Foreign individuals should provide Form W-8BEN and foreign entities Form W-8BEN-E.12Internal Revenue Service. Instructions for Form W-8BEN (Rev. October 2021)13Internal Revenue Service. About Form W-8 BEN-E, Certificate of Status of Beneficial Owner for United States Tax Withholding and Reporting (Entities) Redirect any vendor who tells you they’re foreign to the right W-8 rather than accepting a W-9.
The LLC Complication
LLCs are where the corporate exemption trips people up. The same business structure can be taxed as a sole proprietorship, a partnership, a C corporation, or an S corporation, and the tax classification decides whether the exemption applies. On the W-9, an LLC checks the LLC box on line 3a and enters a code: C, S, or P.3Internal Revenue Service. Form W-9 (Rev. March 2024) Request for Taxpayer Identification Number and Certification An LLC taxed as a C or S corporation is exempt like any other corporation. An LLC taxed as a partnership or a disregarded entity is fully reportable. Single-member disregarded LLCs also have specific name and TIN rules that, if misapplied, cause TIN mismatches and can drop the vendor into backup withholding.14Internal Revenue Service. Instructions for the Requester of Form W-9
Collect Early, Store Carefully
The cleanest policy is a hard gate: no W-9, no first payment. Once a vendor has been paid, leverage disappears, and chasing paperwork becomes an ongoing task nobody enjoys. Even with the higher $2,000 threshold, collecting from every new service vendor at onboarding is cheaper than sorting out who crossed the line in December.
W-9s contain SSNs and EINs, which makes them a breach liability. Every state has notification laws that apply if the information is compromised, so W-9s belong in the same secured, access-restricted storage as other sensitive personal data. The IRS requires employment tax records to be kept at least four years after the tax is due or paid.15Internal Revenue Service. Topic No. 305, Recordkeeping W-9s aren’t employment tax records, but a four-year hold after the last related 1099 filing is the common practice, matching the general examination window. Holding longer just widens the breach exposure without adding compliance value, so purge on a schedule.