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Thirteen common W-9 mistakes

Almost every W-9 problem traces back to a short list of errors, and nearly all of them cluster around Line 1, Line 3a and Part I. Here is each one, what it causes, and the fix.

By The W9Form.org Editorial Team Updated Reviewed against Form W-9 (Rev. March 2024)
Use this as a pre-send checklist

Read down the list before you sign. The whole review takes about a minute and saves the B notice correspondence that otherwise arrives eight months later.

Mistakes on Line 1 and Line 2

Line 1 causes more trouble than every other field on the form combined. It is the line the IRS actually matches against the number in Part I, so an entry that reads perfectly well to a human being and wrongly to a computer produces a mismatch that surfaces months later, in a notice, addressed to your client. Four errors account for nearly all of it. Three of them come from treating Line 1 as the place to say what your business is called. The fourth is paperwork you never got around to.

Name errors
1
A business name on Line 1 with a personal TIN in Part I. This is the single most common error on the form: the IRS matches Line 1 against Part I, and a trade name is nowhere in its records. Put your legal name on Line 1 and the business name on Line 2. Detail
2
Line 1 left blank. An entry is required and the form is invalid without one, so enter the name that matches the TIN.
3
A name that no longer matches SSA records. You married, divorced, or changed your name legally and never told the Social Security Administration, so every payer will mismatch. Update the SSA record first, then recertify. Detail
4
Both names crammed onto Line 1. "Priya Raghavan dba Raghavan Web Design" is a string the IRS cannot match. Split it across Lines 1 and 2.

Mistakes on Line 3a

Classification errors
5
Checking the LLC box for a disregarded single-member LLC. A one-member LLC with no elections checks the first box and reports its owner: first box, owner on Line 1, owner TIN in Part I. Detail
6
Checking the LLC box and leaving the letter space empty. The letter is mandatory, and it is C, S or P. Which letter
7
Leaving Line 3a blank because no box says "nonprofit" or "sole proprietor". Sole proprietors use the first box; nonprofits use Other with a description. All seven boxes
8
Checking two boxes. Exactly one belongs to you, and an LLC with an S election does not also check the S corporation box.

Mistakes on Line 4

Exemption code errors
9
An individual entering an exempt payee code. There is no code that fits a human being, so leave both boxes blank. The codes
10
A private company entering FATCA code D. Code D requires stock regularly traded on an established securities market. Leave it blank. The codes

Mistakes in Part I and Part II

TIN and signature errors
11
A disregarded entity’s own EIN in Part I, which the face of the form prohibits in bold. Use the owner’s SSN or EIN. Why
12
A number in both Part I boxes, or a number with the wrong digit count. All three TIN types have nine digits. One box, nine digits. Detail
13
Typing your name in the signature field, which is generally not a valid signature. Sign by hand, apply a genuine digital signature, or use the requester’s e-signature system. Requirements

Process mistakes that are not on the form at all

Handling errors
MistakeConsequenceBetter approach
Mailing the form to the IRSIt goes nowhere and the payer still has no TINSend it to the requester only. Detail
Emailing it as a plain attachmentYour SSN sits in two mailboxes indefinitelyUse a portal or encrypted transfer. Options
Keeping no copyYou cannot show what you submitted when a 1099 is wrongSave a dated copy of every form you send
Sending the same scan for yearsSome requesters reject a stale date; details may have changedRe-sign and re-date for each requester
Not updating payers after a changePayers file 1099s against outdated informationRecertify on any change of name, entity or TIN. Triggers
Filling the PDF inside a browser previewThe form arrives blankDownload first, then open in a real PDF reader
Using the October 2018 revisionNo Line 3b; the form may be rejectedDownload the current revision

How to correct a form you already sent

Nothing about a bad W-9 is unfixable, and the fix is short. There is no amendment procedure, no correction form, and nobody to notify apart from the payer who holds the wrong version. You replace it, you say in one line what changed, and you ask the one question that decides whether anything else needs doing: has a 1099 already gone out under the old details? If the answer is no, the whole matter ends there.

  1. Complete a clean, corrected form

    Do not annotate the old one. Fill in a fresh W-9, sign it, and date it today.

  2. Send it with one sentence of explanation

    Please replace the Form W-9 I sent on [date]; the earlier version showed the wrong [name / TIN / classification]. That is sufficient.

  3. Ask whether a 1099 has already been filed

    If it has, the payer needs to file a corrected return. Raising it early is far cheaper than an IRS notice for both of you.

  4. Fix the underlying record if that is the problem

    A name mismatch caused by an outdated SSA record will keep recurring until the SSA record is corrected. The same goes for an EIN issued under a different name: request an IRS Letter 147C to confirm what the IRS actually holds.

  5. Claim any withholding back on your return

    Amounts withheld appear as federal income tax withheld on your 1099 and are credited when you file. Detail

Frequently asked questions

What is the most common W-9 mistake?

Putting a business name on Line 1 when the TIN in Part I belongs to an individual. It is the direct cause of most name and TIN mismatch notices.

How do I correct a W-9 I already sent?

Complete a fresh form with the correct entries, sign and date it today, and ask the requester to replace the earlier one. Also ask whether a 1099 has already been filed, because a corrected return may be needed.

Will a small mistake trigger backup withholding immediately?

Not immediately. A mismatch surfaces when the IRS matches the filed 1099, which produces a CP2100 notice to the payer and a B notice to you. Withholding starts if that is not corrected. The cycle

Can I cross out an error and initial it?

Complete a clean form instead. The only crossing-out the instructions contemplate is striking certification item 2 where the rules require it.

Check your entries with the worksheet Read the line-by-line instructions

General information, not tax advice. This page explains a federal tax form in plain English. It is not legal, tax, or accounting advice, and W9Form.org is not affiliated with the IRS. Verify everything against the official Form W-9 page on IRS.gov and speak to a licensed professional about your own situation. How we source and review these pages.