What Is a W-9 and Why Does Your Bookkeeper Need One Before You Pay a Vendor?

What Is a W-9 and Why Does Your Bookkeeper Need One Before You Pay a Vendor?

Form W-9 is the request a business sends a payee to collect their legal name, entity type, and taxpayer identification number, along with a signed certification that the number is correct and that the payee is not subject to backup withholding. You keep it in your files. You never send it to the IRS. Its whole job is to make your year-end information returns accurate, and to protect you if they are not.

That is what a W-9 is. The more useful question is why your bookkeeper wants it before the first payment rather than in January, and the answer is money.

Why Before the First Payment Matters

Once a vendor has been paid, your only real incentive is gone.

A contractor who is waiting on $9,000 will return a completed W-9 within the hour. The same contractor, paid in full six months ago, may not answer at all, and a meaningful share of them will have moved on, dissolved the entity, or simply stopped reading email from a former client.

Then January arrives and you have a payment you cannot report correctly. That is not a paperwork inconvenience. A missing or incorrect taxpayer identification number can trigger backup withholding at 24% on reportable payments, and the payer is liable for amounts that should have been withheld. You can end up remitting 24% of a payment you already made in full, out of your own pocket, with a collection problem against a vendor who has no reason to help you.

Collecting the form first costs nothing. Collecting it late can cost a quarter of the payment.

Who You Need One From, and Who You Do Not

The short rule: collect one from every new vendor, and let your bookkeeper decide later what is reportable. Over-collecting is free. Under-collecting is not.

That said, here is roughly how it sorts out.

Payee type	W-9 needed	Typically reportable on a 1099
Individual, sole proprietor, single-member LLC	Yes	Yes, for services
Partnership or multi-member LLC	Yes	Yes, for services
C or S corporation	Yes, collect it anyway	Generally no, with exceptions
Attorney or law firm, any entity type	Yes	Yes, including corporations
Landlord receiving rent	Yes	Yes, for trade or business rent
Vendor selling goods only	Yes, collect it anyway	Generally no
Foreign person or entity	No, use the W-8 series	Different regime entirely

The corporate exception is the one that trips people up, because it has holes. Payments to corporations are generally not reportable on Form 1099-NEC, but payments to attorneys are reportable even when the law firm is a corporation, and certain medical and health care payments to corporations are reportable as well. The only way to know a vendor is a corporation is to have the W-9 that says so, which is the argument for collecting from everyone and sorting afterward.

What Changed for 2026

The reporting threshold moved. For payments made on or after January 1, 2026, the reporting threshold for Forms 1099-NEC and 1099-MISC rose to $2,000, up from the long-standing $600.

That means fewer forms. It does not mean fewer W-9s, for two reasons. You often do not know at the start of a relationship whether a vendor will cross $2,000 by December, and backup withholding rules track whether a payment is reportable, so the W-9 is what determines your exposure either way.

Anyone treating the higher threshold as permission to stop collecting W-9s has made the wrong inference from it.

Where the W-9 Ends and the 1099 Begins

They are two halves of one process, and mixing them up is common.

The W-9 is inbound. The vendor fills it out, you keep it, nobody files it.

The 1099 is outbound. You file it with the IRS and send a copy to the vendor after year end, and every field on it comes from the W-9. The legal name and TIN on the 1099 must match what the IRS has on record, or you get a notice asking you to correct it, and repeated mismatches are what put a payee into backup withholding.

The entity type box on the W-9 is also what determines which form and which box gets used. Nonemployee compensation for services goes on Form 1099-NEC. Rent, certain other income, and gross proceeds paid to an attorney go on Form 1099-MISC in different boxes. Your bookkeeper cannot make that call without the form.

Foreign Vendors Need a Different Form

A W-9 certifies that the payee is a US person. A foreign contractor or foreign entity is the wrong fit for it, and asking them to sign one is asking them to certify something untrue.

The W-8 series covers non-US payees, most commonly Form W-8BEN for foreign individuals and Form W-8BEN-E for foreign entities. Those forms address a separate regime with its own withholding rates and treaty claims, and getting it wrong has real consequences. If you are paying anyone outside the US, that is a question for your accountant before the first payment, not a form to guess at.

Where This Fits in the Rest of Your Process

Vendor onboarding is one of the few places where a small process change eliminates an entire category of January work. The W-9 belongs in the same step as the signed agreement and the banking details, before anything is scheduled for payment. The rest of the vendor file has its own failure modes, covered in 6 Accounts Payable Habits That Quietly Cost a Growing Business Money.

System Six is a Seattle firm founded in 2009 with a team of forty-one, serving clients nationwide as a bookkeeper, accountant, and fractional CFO with a stated focus on day to day finance operations. Seventeen years of doing exactly this kind of routine work for SMB owners and real estate investors is the relevant qualification, since vendor onboarding discipline is not a strategy problem, it is an operations habit that either exists or does not.

Bringing in an outside team can install the habit and keep it running. It also costs money, it does not retroactively produce forms from vendors who have already been paid, and it does not remove the business owner's responsibility for the accuracy of the returns filed under their name.

If your vendor file has gaps, compare firms that handle payables and information reporting in the Sam's List bookkeeper directory and read verified client reviews before you get on a call.

Frequently Asked Questions

Do I send Form W-9 to the IRS? No. The payer collects Form W-9 from the payee and keeps it in their own records. It is never filed with the IRS. Its purpose is to supply the legal name, entity classification, and taxpayer identification number that the payer will use to prepare year-end information returns such as Form 1099-NEC.

What happens if a vendor refuses to provide a W-9? The payment is treated as subject to backup withholding, which means withholding at 24% and remitting that amount to the IRS. The payer is liable for amounts that should have been withheld, so the practical protection is to make a completed W-9 a condition of the first payment rather than a request made afterward.

Do I need a W-9 from a corporation? Collect one regardless. Most payments to corporations are not reportable on Form 1099-NEC, but the exceptions matter, including payments to attorneys and certain medical and health care payments. The W-9 is how you document the entity classification that supports not filing a form, which is the record you want if the treatment is ever questioned.

Is the W-9 threshold still $600? No. For payments made on or after January 1, 2026, the reporting threshold for Forms 1099-NEC and 1099-MISC increased to $2,000. The W-9 itself has no threshold. Collect it at onboarding, because you rarely know at the start which vendors will cross the line by year end.

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About the author: Kimberly Green is the cofounder of Sam's List, where business owners and high earners find vetted CPAs, financial advisors, and fractional CFOs. She's met one-on-one with 400+ financial professionals and writes from the real data behind thousands of client-advisor matches. Ask her anything about finding an accountant - she's heard it all, including the questions people are afraid to ask.