What Causes a TIN/Name Mismatch?

Eliminate vendor mismatches before they trigger IRS notices with real-time TIN validation and automated W-9 correction workflows.

What Causes a TIN/Name Mismatch?

A TIN/Name mismatch occurs when the Taxpayer Identification Number (TIN) and legal name submitted by a business do not match the official records on file with the IRS. This is one of the most common compliance issues businesses face during vendor onboarding and 1099 filing, and it often leads to IRS notices such as CP2100 (B-Notice trigger) or 972CG (penalty notice).

A mismatch does not always mean fraud. In most cases, it’s caused by formatting issues, outdated information, or vendors submitting the wrong name or TIN type.

Even small name differences like “Inc.” vs no “Inc.” can cause a mismatch.

What is a TIN/Name Mismatch?

A TIN/Name mismatch means:

  • The TIN (EIN, SSN, or ITIN) does not match IRS records
  • The legal name does not match IRS records
  • Or the combination of the name and TIN does not match what the IRS expects

The IRS matching process is strict because taxpayer reporting must be accurate.

A TIN can be valid, but still fail if the legal name does not match exactly.

The Most Common Causes of TIN/Name Mismatch

Below are the most frequent reasons businesses receive mismatches when validating vendor data.

Many vendors provide a DBA (Doing Business As) name or trade name rather than their IRS legal entity name.

Example:

Vendor submits:

  • FastFix Plumbing

IRS legal name:

  • Robert Taylor Services LLC

Result: mismatch.

The IRS matches against the legal name tied to the TIN—not the marketing name.

2. Missing Business Suffix (LLC, Inc., Corp)

Businesses often leave off legal suffixes, which can trigger mismatches.

Common suffixes include:

  • LLC
  • Inc.
  • Corporation
  • Ltd
  • LLP
  • LP

Example:

Vendor submits:

  • Apex Logistics

IRS legal name:

  • Apex Logistics, Inc.

Result: mismatch.

Missing “LLC” or “Inc.” is one of the most common mismatch causes.

3. Incorrect EIN or SSN (Typos and Data Entry Errors)

Even a single digit error will cause a mismatch.

Common data entry mistakes include:

  • transposed digits
  • missing digits
  • incorrect digit typed
  • extra spaces or punctuation
  • copied incorrectly from a PDF or email

Example:

Correct EIN: 12-3456789
Submitted EIN: 12-3456879

Result: mismatch.

This is especially common when vendor data is entered manually into ERP or AP systems.

4. Wrong TIN Type (EIN vs SSN Confusion)

This is very common for:

  • sole proprietors
  • independent contractors
  • single-member LLCs

A vendor may provide an EIN, but the IRS expects the SSN (or vice versa) depending on how the vendor is registered.

Example:

Vendor submits:

  • Legal Name: John Smith
  • EIN: 22-3344556

IRS expects:

  • John Smith + SSN

Result: mismatch.

Many small vendors don’t understand which taxpayer name/TIN combination is correct.

Vendors may change their legal structure due to:

  • mergers or acquisitions
  • entity conversion (LLC to corporation)
  • ownership change
  • name change filed with IRS
  • divorce/marriage name change (individuals)

If your records are outdated, the IRS may return a mismatch.

Vendor records that were correct last year may be wrong this year.

6. Incorrect Spelling or Punctuation in the Name

Small formatting issues can cause mismatches, including:

  • missing commas
  • hyphens
  • apostrophes
  • periods
  • inconsistent capitalization
  • extra spaces

Example:

Vendor submits:

  • O'Brien Consulting LLC

IRS record:

  • OBrien Consulting LLC

Result: mismatch.

These are frustrating mismatches because the vendor is legitimate—but the formatting is different.

7. Middle Initial or Name Variation Issues (Individuals)

Individual name formatting mismatches are very common.

Example:

Vendor submits:

  • Sarah M. Johnson

IRS record:

  • Sarah Johnson

Result: mismatch.

Other common issues:

  • nicknames (Mike vs Michael)
  • missing middle name
  • married name not updated
  • incorrect last name spelling

Contractors often enter their “preferred name,” not their IRS name.

8. Using Business Name Field Incorrectly on the W-9

Some vendors misunderstand the W-9 fields and enter:

  • business name in the individual name line
  • individual name in the business name line
  • both names incorrectly

This creates mismatches when the payer stores the wrong name as the legal name.

W-9 errors are one of the biggest drivers of TIN/name mismatches.

9. Incorrect Vendor Record Imported from ERP or AP Systems

Vendor data is often copied between systems, such as:

  • SAP
  • Oracle
  • Workday
  • NetSuite
  • Coupa
  • QuickBooks

During migration or import, name fields may be truncated or reformatted.

Example:

  • “International Distribution Holdings, LLC” becomes “International Distrib Hold”

Result: mismatch.

Vendor master file quality issues are a major cause of IRS mismatch risk.

10. Vendor Provided the Wrong Taxpayer Entity

Sometimes a vendor provides the EIN of one entity but the name of another entity.

Example:

Vendor submits:

  • Name: ABC Construction LLC
  • EIN: (belongs to ABC Holdings Inc.)

Result: mismatch.

This can happen when:

  • parent company and subsidiary are confused
  • vendor has multiple entities
  • vendor is using an accounting firm’s information incorrectly

Complex business structures often create mismatch risk.

Examples of TIN/Name Mismatch Scenarios

Example 1: Missing “LLC”

Submitted: BrightLine Consulting
IRS: BrightLine Consulting LLC
Result: mismatch

Example 2: Typo in EIN

Submitted: 45-9876123
Correct: 45-9876213
Result: mismatch

Submitted: Mike’s Plumbing
IRS: Michael Carter Services LLC
Result: mismatch

Example 4: Name Variation for Individual

Submitted: John A. Smith
IRS: John Smith
Result: mismatch

These issues are extremely common and often easy to fix once identified.

Common Mistakes Businesses Make That Increase Mismatches

Organizations often unintentionally create mismatch risk by:

  • allowing vendor setup without a signed W-9
  • relying on outdated vendor master data
  • skipping validation until filing season
  • not using IRS TIN matching at onboarding
  • storing DBA names instead of legal names
  • manually retyping vendor information instead of collecting it digitally

Most mismatches are preventable with consistent onboarding workflows.

How to Prevent TIN/Name Mismatches

Here are the best ways to reduce mismatches:

Require W-9 completion before payment
Validate vendor name and TIN during onboarding
Revalidate vendor lists annually before filing season
Use the vendor’s legal entity name, not DBA name
Automate mismatch outreach and correction workflows
Maintain audit-ready validation history

Prevention is the easiest way to reduce CP2100 and 972CG notices.

Frequently Asked Questions (FAQ)

Does a TIN/name mismatch mean the vendor is fraudulent?

No. Most mismatches are caused by formatting errors, missing suffixes, or vendors using DBA names instead of legal names.

Can a valid EIN still return a mismatch?

Yes. The EIN can be valid, but if the legal name does not match IRS records, the combination will fail validation.

What is the fastest way to fix a mismatch?

Request an updated W-9 from the vendor and validate the corrected name/TIN combination before filing.

How do mismatches impact 1099 filing?

Mismatches can trigger IRS notices, increase correction workload, and lead to penalties if not resolved.

How can mismatches be prevented at scale?

Bulk validation and API-based TIN matching are the most effective ways to prevent mismatches across large vendor master lists.

Conclusion

TIN/name mismatches are most commonly caused by vendors submitting DBA names, missing legal suffixes like LLC or Inc., typos in EIN/SSN numbers, or outdated W-9 information. By validating vendor records early and maintaining clean legal entity data, organizations can prevent mismatches before filing season and reduce IRS compliance risk.

Prevent TIN/Name Mismatches with TIN Comply

TIN Comply helps organizations reduce TIN/name mismatches by validating vendor records against IRS data in real time. With manual checks, bulk file processing, API integration, and audit-ready reporting, TIN Comply makes it easy to correct vendor data early and avoid CP2100 notices, B-Notices, and 972CG penalties.

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