How to Fill Out a W-9 Form: A Step-by-Step Guide

Completing a Form W-9 is often one of the first administrative steps in a new independent contractor or vendor relationship. 

That’s because a W-9 provides the payer with the information needed to report certain payments to the IRS, including your legal name, address, and Taxpayer Identification Number (such as a Social Security number or EIN). Businesses use this information to issue Form 1099s when required.

Freelancers submit Form W-9  to clients, vendors provide it during onboarding, and businesses request it before issuing certain reportable payments so they can determine whether a Form 1099 is required.

The information reported on a W-9 is used for federal tax reporting, and incorrect details can create avoidable complications, so learning how to fill out a W-9 Form is essential. Although the form appears straightforward, it carries legal and tax significance. The legal name must align with IRS records, the taxpayer identification number (TIN) must be accurate, and the certification is signed under penalty of perjury. Understanding how each section applies to a specific business structure helps ensure accurate reporting from the start.

This blog post is offered for general information purposes only. It does not constitute, and is not a substitute for, legal or tax advice.

What does Form W-9 do?

Form W-9, officially titled Request for Taxpayer Identification Number and Certification, is used by businesses to collect tax identification information from individuals and entities they pay. The person completing the form does not file it with the IRS. Instead, the form is provided to the requesting organization so that accurate information can be used for year-end reporting.

Businesses typically request a W-9 when engaging with:

• Independent contractors

• Freelancers

• Consultants

• Vendors

• Certain service providers

The form allows the payer to properly associate payments with the correct taxpayer under federal reporting rules. The information collected on Form W-9 is typically used to prepare information returns, such as Form 1099-NEC or other required reporting documents, when applicable. Accurate completion helps ensure that income is reported under the correct name and taxpayer identification number at year-end.

A W-9 does not:

• Establish employment status

• Replace a contract or service agreement

• Adjust tax withholding elections

• Function as a tax return

Its purpose is limited but important: to collect accurate identification information for reporting. It supports compliance, but it does not define the underlying legal or tax relationship between the parties.

How to fill out Form W-9 based on your business structure

Although every payer uses the same Form W-9, how you complete certain sections depends on how your business is structured for federal tax purposes. Most reporting problems arise when the legal name, tax classification, and taxpayer identification number do not align.

Before entering information, confirm how the business is treated for federal tax purposes. The IRS might classify your business differently from your state registration, and federal classification determines how you complete the form.

How to fill out Form W-9 as an individual or independent contractor

This category includes freelancers and service providers who have not formed a separate legal entity. If you fall into this group, you are part of a massive shift in the labor market: it is projected that by 2027, 86.5 million people will be freelancing in the United States, representing 50.9% of the total U.S. workforce.

Even if services are marketed under a business name, income is typically reported under the individual’s Social Security number unless an Employer Identification Number (EIN) has been obtained.

To complete the form:

• Enter your personal legal name on Line 1

• Leave Line 2 blank unless you operate under a registered trade name (DBA)

• Select “Individual/sole proprietor” as your federal tax classification

• Provide your Social Security Number (SSN) or EIN if one has been obtained

Even if invoices display a business name, the IRS matches the TIN to the legal name listed on Line 1, and only recognizes that name when processing tax documents.

How to fill out Form W-9 for sole proprietors using trade names

Some sole proprietors operate under a business or brand name that differs from their personal legal name. This does not create a separate taxable entity, but it does affect how the name fields should be completed.

To complete the form:

• Enter your personal legal name on Line 1

• Leave line 2 blank unless you operate under a registered trade name (DBA). Enter the trade name on Line 2

• Select “Individual/sole proprietor as your federal tax classification

• Provide your SSN or EIN if one has been obtained

Even if invoices display a business name, the IRS matches the TIN  to the legal name listed on Line 1 and only recognizes that name when processing tax documents.

How to fill out Form W-9 for Single-Member LLCs (disregarded entities)

Single-member LLCs create frequent confusion. Forming an LLC under state law does not automatically change how the IRS treats the business for federal tax purposes. By default, many single-member LLCs are treated as “disregarded entities,” meaning income is reported under the owner’s tax identification number.

If the LLC is treated as a disregarded entity:

• Enter the owner’s legal name on Line 1

• Enter the LLC name on Line 2

• Select “Individual/sole proprietor” unless the LLC has elected to be taxed as a corporation

• Provide the owner’s SSN, or the LLC’s EIN if one has been obtained

Even if contracts and invoices display the LLC name, the IRS matches reporting to the owner when the LLC is disregarded.

If the LLC has elected corporate taxation, the reporting requirements follow corporate rules instead.

How to fill out Form W-9 for multi-member LLCs or partnerships

When an LLC has more than one member and has not elected corporate taxation, it is generally taxed as a partnership. In this case, the business itself is the reporting entity.

To complete the form:

• Enter the registered business name on Line 1

• Leave Line 2 blank unless using a separate trade name

• Select “Partnership” or the applicable LLC classification

• Provide the business EIN

Income is typically reported to the entity using its EIN.

How to fill out Form W-9 for corporations (C or S)

Corporations are separate taxable entities. Reporting is straightforward because the legal name and EIN correspond directly to the corporation.

To complete the form:

• Enter the registered corporate name on Line 1

• Select “C corporation” or “S corporation” as applicable

• Provide the corporate EIN

Many corporations are exempt from backup withholding, although exemption codes may apply in certain circumstances.

Common W-9 mistakes to avoid

Most W-9 issues are not caused by complex tax rules but by small inconsistencies or overlooked details. Because the form supports federal reporting, even minor errors can trigger follow-up requests, corrected filings, or payment delays.

Reviewing the form carefully before submission helps prevent unnecessary complications. In the 2024 fiscal year, the IRS processed more than 266 million tax returns and other forms, highlighting the scale of administrative tax reporting where accurate identification information matters.

Name and TIN mismatches

The most common W-9 issue is a mismatch between the legal name entered on Line 1 and the taxpayer identification number (TIN) provided. Because the IRS validates reporting by matching these two elements, even minor inconsistencies can trigger administrative notices.

These mismatches typically result from practical errors rather than intentional misreporting. Common causes include:

• Entering a business or trade name on Line 1 when the TIN belongs to an individual

• Providing an outdated or incorrectly issued EIN

• Transposing digits in a Social Security Number

• Listing an LLC name on Line 1 when the TIN corresponds to the owner of a disregarded entity

• Using a nickname or abbreviated version of a legal name

If the name and TIN do not align with IRS records, the payer may receive a CP2100 or CP2100A Notice requiring verification. In certain cases, backup withholding at a flat 24% rate may apply until the discrepancy is resolved. These issues can also delay vendor onboarding or payment processing, particularly for organizations managing high volumes of contractor relationships.

Incorrect entity classification

Federal tax classification determines how payments are reported at year-end and whether certain reporting exemptions apply. Selecting the wrong classification does not usually invalidate the form immediately, but it can create confusion when preparing information returns such as Form 1099-NEC.

Classification errors frequently arise when business structure and tax treatment are confused. Examples include:

• Checking “Individual/sole proprietor” when the business is taxed as a partnership

• Selecting “LLC” without specifying the appropriate tax classification

• Failing to reflect a corporate tax election made with the IRS

• Assuming state registration automatically determines federal tax treatment

An LLC, for example, may be taxed as a sole proprietorship, partnership, or corporation depending on elections filed with the IRS. The selection on the W-9 must reflect how the entity is treated for federal tax purposes — not simply how it is organized under state law.

If uncertainty exists, confirm the entity’s federal tax classification before completing the form. Aligning classification with the TIN provided ensures accurate reporting and reduces the likelihood of correction requests later.

Missing or incomplete certification

The certification section gives the W-9 its legal force. Without a signature and date, the form is incomplete and cannot be relied upon for reporting purposes.

Common certification issues include:

• Forgetting to sign the form

• Failing to date the certification

• Leaving required fields incomplete

• Submitting an outdated version of the form

By signing, the individual or authorized representative confirms that the TIN provided is correct, that the entity is not subject to backup withholding (unless indicated), and that the signer qualifies under the stated requirements.

Because the certification is made under penalty of perjury, it should not be treated as a routine administrative step. A brief review before signing helps ensure that the information entered throughout the form is accurate and consistent.

For businesses collecting W-9 forms at scale, confirming that each submission is complete and properly certified is an important control within the broader tax reporting process.

Streamlining the W-9 process with secure digital workflows

A Form W-9 contains sensitive information, so how it is collected, transmitted, and stored matters just as much as how it is completed. For organizations managing multiple contractors or vendors, paper-based or email-based collection methods create avoidable risk. Unencrypted attachments, incomplete forms, and version control issues often result in delays or follow-up requests.

With IRS projections showing information returns potentially rising to around 5 billion annually by 2028, managing high-volume W-9 collection and reporting obligations with professional templates and structured, secure digital processes is becoming increasingly important. 

Using these processes can help reduce issues by:

• Standardizing how W-9 requests are issued

• Ensuring required fields are completed before submission

• Securing transmission of sensitive tax information

• Maintaining centralized storage for audit and reporting purposes

• Creating a record of when and how the form was signed

Electronic completion and signature are permitted for Form W-9, provided the system used meets IRS requirements for authentication, integrity, and record retention. 

For enterprises handling large volumes of contractor onboarding, integrating W-9 collection into broader agreement management or vendor setup processes reduces friction. When tax documentation is aligned with contract execution and payment workflows, administrative follow-up is minimized, and reporting accuracy improves. 

A consistent digital approach does not change the information required on a W-9, but it significantly reduces the operational risk associated with collecting and maintaining that information at scale.

Frequently asked questions

What information do I need to fill out a W-9 form?

You will need your legal name, business name (if different), federal tax classification, mailing address, and taxpayer identification number (SSN or EIN). The form must also be signed and dated.

Who needs to fill out a W-9 form?

Independent contractors, freelancers, vendors, and certain service providers typically complete Form W-9 when requested by a payer for reporting purposes.

What happens if I make a mistake on my W-9?

If incorrect information is submitted, the payer may request a corrected form. Name and TIN mismatches can trigger verification notices and potentially backup withholding until resolved.

Do I need to sign a W-9 form?

Yes. The certification must be signed and dated. Without a signature, the form is incomplete.

Can I fill out a W-9 form electronically?

Yes. The IRS permits electronic W-9 completion and signature, provided the system meets authentication and record-retention standards.

What is the difference between W-9 and W-4 forms?

Form W-9 collects taxpayer identification information for reporting nonemployee compensation. Form W-4 is used by employees to determine federal income tax withholding from wages.

How often do I need to update my W-9 information?

You should provide an updated W-9 if your legal name, business structure, or taxpayer identification number changes.

What is a TIN on a W-9 form?

A TIN (Taxpayer Identification Number) is either a Social Security Number (SSN) or an Employer Identification Number (EIN) used to identify a taxpayer for reporting purposes.