What is a CP2100 Notice?

Stop CP2100 Notices before they happen with real-time IRS TIN matching and automated vendor validation.

What is a CP2100 Notice?

A CP2100 Notice is an IRS notice sent to businesses when the IRS identifies a mismatch between the Taxpayer Identification Number (TIN) and name reported on submitted information returns, such as Form 1099. It is often referred to as a “B-Notice” letter, because it triggers specific compliance requirements for contacting vendors and potentially initiating backup withholding.

If your organization receives a CP2100 Notice, it means the IRS is informing you that one or more payees (vendors, contractors, suppliers, or recipients) had incorrect taxpayer information on the forms you filed.

CP2100 Notices are serious because failure to respond correctly can result in penalties and increased IRS compliance risk.

What Causes a CP2100 Notice?

A CP2100 Notice is issued when the IRS cannot match the Name/TIN combination reported on your filed 1099 forms to their records.

Common reasons include:

  • Incorrect EIN or SSN (typo or transposed digits)
  • Vendor used a DBA name instead of legal IRS name
  • Missing business suffix (LLC, Inc, Corp)
  • Vendor changed entity structure or legal name
  • Incorrect tax classification or outdated W-9
  • Data entry issues from ERP/AP systems

The IRS is essentially saying: “The information you filed does not match what we have on record.”

What Does the CP2100 Notice Mean?

A CP2100 Notice is the IRS informing you that you reported incorrect payee information and must take corrective action.

It typically means:

The vendor name/TIN combination did not match IRS records
You may be required to send the payee a formal B-Notice
You may be required to begin backup withholding
You may need to request a new W-9 form

A CP2100 Notice may include a list of vendors/payees and error codes indicating the mismatch reason.

CP2100 Notice vs CP2100A Notice

The IRS issues two similar notices:

  • CP2100 Notice (paper notice, typically mailed)
  • CP2100A Notice (often electronic or formatted differently, usually for larger filers)

Both notices serve the same purpose: they identify payee name/TIN mismatches and instruct the filer on required corrective actions.

Most organizations treat CP2100 and CP2100A as the same compliance workflow.

What is a B-Notice?

A B-Notice is the official written notification you must send to a vendor/payee when the IRS reports a name/TIN mismatch.

There are two types:

First B-Notice

Sent after the first mismatch is reported for that vendor.

You request that the vendor confirm or correct their name/TIN by completing a new W-9.

Second B-Notice

Sent if the same vendor is flagged again after a first B-Notice was already issued.

A second B-Notice requires the vendor to provide documentation from the IRS or SSA confirming the correct TIN.

What Happens If You Receive a CP2100 Notice?

When you receive a CP2100 Notice, you must follow IRS instructions to remain compliant.

Typical steps include:

Review the vendor list included in the notice
Identify which vendors had mismatches
Send the required B-Notices
Request updated W-9 forms
Begin backup withholding if required
Maintain documentation and audit trail

The IRS expects organizations to complete this process within the deadlines specified in the notice.

CP2100 Notice Example Scenario

Let’s say your organization files 1099-NEC forms for contractors.

You submit:

  • Vendor Name: Brightline Consulting
  • TIN: 12-3456789

The IRS records show the legal entity name as:

  • Brightline Consulting Group, LLC

The IRS cannot match the record and issues a CP2100 Notice listing that vendor.

Even though the vendor may be legitimate, the mismatch can still trigger the notice.

Your organization must contact the vendor and request corrected information.

What is Backup Withholding?

Backup withholding is an IRS requirement where a payer must withhold a percentage of payments made to a vendor if the vendor’s taxpayer information is incorrect or not properly provided.

Backup withholding is commonly triggered when:

  • a vendor fails to provide a valid TIN
  • a vendor fails to respond to a B-Notice
  • repeated IRS mismatches occur

Backup withholding is a compliance burden for AP and payroll teams and can create vendor relationship issues if not handled properly.

Common Mistakes Businesses Make After Receiving a CP2100 Notice

Organizations often create compliance risk by responding incorrectly or too slowly.

Common mistakes include:

1. Ignoring the Notice

Some organizations assume the notice is informational only. It is not.

Failure to respond can result in penalties and audit exposure.

2. Not Sending B-Notices Correctly

B-Notices have specific IRS requirements, including timelines and required wording.

3. Not Collecting Updated W-9 Forms

A corrected W-9 is often the simplest way to resolve a mismatch.

4. Waiting Until Year-End to Fix Vendor Data

Delaying resolution increases the likelihood of repeat mismatches and larger compliance workload.

5. Poor Recordkeeping

Organizations should retain proof of B-Notice delivery and updated vendor documentation.

Documentation is critical if the IRS requests proof of compliance.

How to Prevent CP2100 Notices

The best way to reduce CP2100 notices is to validate vendor records before filing 1099 forms.

Best practices include:

  • Collect a signed W-9 during vendor onboarding
  • Validate the vendor name and TIN using IRS TIN matching
  • Revalidate vendor lists annually before filing season
  • Run bulk validation for vendor master data cleanup
  • Use automated workflows to correct mismatches quickly
  • Maintain audit-ready records of validations and corrections

Preventative validation is significantly cheaper than resolving CP2100 notices after filing.

Frequently Asked Questions (FAQ)

Is a CP2100 Notice the same as a B-Notice?

Not exactly. A CP2100 Notice is the IRS notifying you of mismatched vendor information. A B-Notice is the letter you must send to the vendor as part of the required corrective process.

Does a CP2100 Notice mean the vendor is fraudulent?

No. Most CP2100 mismatches are caused by typos, DBA names, missing suffixes (LLC/Inc), or outdated W-9 information.

Do I have to start backup withholding immediately?

Backup withholding rules depend on whether the vendor responds and whether this is a first or second mismatch. The CP2100 Notice provides guidance, and organizations should follow IRS instructions carefully.

Can CP2100 Notices be avoided?

Yes. The most effective way to reduce CP2100 Notices is to validate vendor TIN and name combinations before filing, using real-time IRS TIN matching.

Do CP2100 Notices apply only to 1099 forms?

They most commonly relate to 1099 filings, but they can apply to other information returns where name/TIN reporting is required.

Conclusion

A CP2100 Notice is an IRS compliance notice issued when the IRS identifies mismatched vendor name and TIN combinations on filed information returns such as 1099 forms. These notices can trigger B-Notice requirements, backup withholding obligations, and potential penalties—making proactive vendor validation a critical best practice for AP, payroll, and compliance teams.

Reduce CP2100 Notices with TIN Comply

TIN Comply helps businesses prevent CP2100 Notices by validating vendor name and TIN combinations before filing season. With real-time IRS TIN matching, bulk file validation, and audit-ready reporting, organizations can reduce mismatches, improve vendor onboarding accuracy, and strengthen tax compliance programs.

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