W-9s for subcontractors: when to ask, why it matters and how to store them
What a W-9 is, when many general contractors collect one from subcontractors, what can happen without one, how long the IRS suggests keeping it, and how to handle it safely.
Not advice. General information only, based on our research of publicly available sources, which can change. It is not legal, insurance, tax or accounting advice. Rules can vary by state, carrier and contract, so please talk to your insurance agent, attorney or tax professional about your situation.
In short: A W-9 is the IRS form a subcontractor fills out to give you their correct name and taxpayer identification number (TIN), which you may need for a 1099. Many GCs collect it before the first payment, because that's when it's usually easiest to get. The IRS says to keep it for four years, and to keep the information on it confidential. Your tax professional can tell you what applies to you.
Chasing W-9s in January is a familiar headache. By then the job may be long over and the sub may be slow to answer. Collecting it up front can avoid much of that. Here's a general overview of what the form does and how many contractors handle it.
What a W-9 is for
The IRS's page on Form W-9 says it's used "to provide your correct Taxpayer Identification Number (TIN) to the person who is required to file an information return with the IRS." For contractors, that information return is often a Form 1099-NEC.
So the sub fills it out and gives it to you. It doesn't go to the IRS. You keep it and use it to prepare any 1099 you're required to file.
When to ask for one
The IRS's page on forms for independent contractors says that once you've determined someone is an independent contractor, "the first step is to have the contractor complete Form W-9."
Many GCs make it part of onboarding a new sub, alongside the certificate of insurance. One practical reason is that a sub who's waiting on a first payment often has a good reason to send paperwork.
Whether a 1099 is required is a separate question, and it depends on what and how much you paid. The IRS's 1099 instructions say the reporting threshold rose to $2,000 for tax years beginning after 2025. Some GCs collect a W-9 from every sub regardless, so it's on file if the total grows. Your tax professional can help you decide.
What could happen without one
Two things worth knowing, and your tax professional can explain how they apply to you:
- Backup withholding. The IRS's backup withholding page describes situations where a payer "is required to withhold at the current rate of 24 percent," including when a correct TIN wasn't provided. Withholding on a sub's payments is rarely a conversation anyone wants to have mid-job.
- Penalties. The IRS's general instructions for information returns say: "You may be subject to a penalty for an incorrect or missing TIN on an information return."
What to look at when one comes in
The IRS's contractor page says the form can be used to request "the correct name and taxpayer identification number" of the payee. A few things many GCs glance at:
- Is it filled in and signed? A blank field or missing signature is easy to catch on day one and harder to fix in January.
- Does the name match the business you're paying? A check to "ABC Framing LLC" and a W-9 in someone's personal name may raise questions worth asking.
- Is it the current version of the form? The IRS's page links to the current revision.
Some payers also use the IRS's TIN Matching service, which "lets you validate TIN and name combinations before submitting an information return." It's limited to certain payers and needs an application, so check the IRS page to see if it fits you.
How long to keep it, and how to store it
The IRS's contractor page says: "The W-9 should be kept in your files for four years for future reference in case of any questions from the worker or the IRS."
A W-9 can hold a Social Security number, so how you store it may matter. The IRS's general instructions say: "You are required to maintain the confidentiality of information obtained on a Form W-9/W-9S relating to the taxpayer's identity." That's one reason some contractors move away from emailing W-9s around or keeping them in a shared folder or a truck. Your tax professional or attorney can advise on what's appropriate for your business.
W-9s and workers' comp audits
A W-9 and a certificate of insurance do different jobs. The W-9 is about tax reporting. The certificate is evidence of insurance. Having one doesn't take the place of the other, and a workers' comp audit may look at 1099s and certificates side by side, so many GCs keep them together.
Frequently asked questions
Do subcontractors need to fill out a W-9?
The IRS says that once you've determined someone is an independent contractor, the first step is to have them complete Form W-9. Many GCs ask for it before the first payment. Your tax professional can tell you what applies to your situation.
Does a W-9 go to the IRS?
No. The sub gives it to you, and you keep it in your files. You use the information to prepare any information return you're required to file, such as a 1099-NEC.
How long should I keep a W-9?
The IRS says the W-9 should be kept in your files for four years for future reference in case of questions from the worker or the IRS.
What if a subcontractor won't give me a W-9?
The IRS describes backup withholding at 24 percent in situations where a correct TIN isn't provided, and penalties may apply for a missing TIN on an information return. A tax professional can tell you how to handle a specific sub.
Do I need a new W-9 every year?
Not necessarily. Many GCs ask for a new one when a sub's name, business structure or TIN changes. Your tax professional can advise on your practice.
How CertiSub is designed to help
CertiSub lets you add W-9s to your required documents, so they can be requested alongside the certificate through a no-login upload link, and automatic follow-ups go out for anything still outstanding. W-9s are stored against the sub with access limited to your own account. You can download all your files and data anytime, on every plan.
This article is for general informational purposes only. It reflects our research of publicly available sources as of its publication date and may not be complete or current. It is not legal, insurance, tax or accounting advice, and reading it does not create any professional relationship. Requirements can vary by state, insurance carrier, policy and contract. Before making decisions, consult a licensed insurance professional, an attorney, or a tax professional about your specific situation. CertiSub is a recordkeeping and document-organization tool. It tracks the documents and dates you provide. It does not verify insurance validity or provide legal, insurance, or compliance advice.