How to Fix a TIN/Name Mismatch

Resolve TIN mismatches fast by collecting corrected W-9 data and validating vendor records against IRS records before filing season.

How to Fix a TIN/Name Mismatch (Step-by-Step Guide)

A TIN/Name mismatch occurs when a vendor’s Taxpayer Identification Number (TIN) and legal name do not match IRS records. This is one of the most common compliance issues for businesses that onboard vendors, issue payments, and file 1099 forms.

The good news is that most mismatches are easy to fix once you understand what caused the issue. With the right process, organizations can correct vendor data quickly, reduce IRS notices, and avoid penalties.

A TIN mismatch is not always fraud—most mismatches are caused by typos, formatting errors, or vendors using the wrong legal name.

What Causes a TIN/Name Mismatch?

Before fixing a mismatch, it helps to understand the most common causes:

Typo in EIN, SSN, or ITIN
Vendor used a DBA instead of the legal IRS name
Missing business suffix (LLC, Inc., Corp)
Incorrect name formatting (punctuation, spacing)
Vendor changed legal name or entity structure
Wrong TIN type used (EIN vs SSN)
Incorrect W-9 form completion

Most mismatches are data issues, not compliance violations.

Step-by-Step: How to Fix a TIN/Name Mismatch

Below is a clear, repeatable workflow to resolve mismatches efficiently.

Step 1: Confirm the Mismatch Result

First, verify exactly what type of mismatch you are dealing with:

  • name mismatch (TIN is valid, name is incorrect)
  • TIN mismatch (name may be correct, TIN is incorrect)
  • both name and TIN incorrect
  • wrong taxpayer type or classification

If your system provides mismatch codes or results, document them.

Always log mismatch results for audit tracking and follow-up.

Step 2: Check for Simple Data Entry Errors

Before contacting the vendor, check for internal errors such as:

  • transposed digits (e.g., 12-3456789 vs 12-3546789)
  • missing digit
  • extra digit
  • wrong punctuation or spacing
  • truncated vendor name (common in ERP systems)
  • incorrect suffix removed (LLC, Inc.)

Many mismatches are caused by manual entry mistakes inside AP systems.

Quick internal checklist:

  • Does the TIN have the correct number of digits?
  • Is the legal name spelled correctly?
  • Is "LLC" or "Inc." missing?
  • Is the vendor record duplicated in your system?

Many vendors submit a DBA name or trade name that does not match IRS records.

Example:

Vendor provides:

  • Name: QuickShip Delivery
  • EIN: 12-3456789

IRS record:

  • QuickShip Delivery Services LLC

Result: mismatch

The IRS matches the legal name tied to the EIN—not the marketing or DBA name.

Step 4: Request a New W-9 Form (Best Practice)

If the mismatch cannot be fixed internally, the next step is to request an updated:

Form W-9

A corrected W-9 should include:

  • legal taxpayer name (Line 1)
  • business/DBA name (Line 2, optional)
  • correct tax classification
  • correct TIN (EIN or SSN)
  • signature and date

Do not rely on verbal corrections. A signed W-9 is the official certification document.

Step 5: Confirm the Vendor Used the Correct TIN Type (EIN vs SSN)

Some vendors (especially sole proprietors) provide the wrong taxpayer ID type.

Common issue:

  • Vendor provides an EIN
  • IRS expects SSN for that taxpayer name
  • Result is a mismatch

To fix this, confirm the vendor’s tax classification:

  • individual/sole proprietor (often SSN)
  • LLC (may be EIN or SSN depending on structure)
  • corporation/partnership (usually EIN)

Sole proprietor mismatches are among the most common and usually require clarification on the correct taxpayer ID.

Step 6: Validate the Corrected Information Using IRS TIN Matching

Once you receive updated vendor information, validate it again using IRS TIN matching.

Validation ensures:

  • the name and TIN match IRS records
  • the record is safe for 1099 filing
  • the mismatch is resolved before year-end

Validation is the fastest way to confirm the mismatch is truly fixed.

Step 7: Update Vendor Master Data in Your ERP/AP System

After validation, update the vendor record in your system of record such as:

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

Make sure to update:

  • legal name
  • TIN
  • tax classification
  • address (if needed)

Fixing the mismatch only in a spreadsheet will not prevent future errors.

Step 8: Re-run Validation for Quality Assurance

After updating the system, re-run the validation to confirm:

the correct name/TIN is now stored
the mismatch no longer appears
future reporting will use the corrected data

This step is often skipped, but it prevents repeat mismatches.

Step 9: Track Documentation for Compliance

Maintain a record of:

  • mismatch result
  • outreach attempts
  • W-9 request sent
  • W-9 received and stored
  • validation confirmation
  • date the vendor record was updated

Documentation is important for audit readiness and B-Notice compliance requirements.

How to Fix a TIN/Name Mismatch Quickly (Fast Checklist)

If you need a quick workflow, follow this checklist:

Check for typos in TIN
Ensure legal name includes LLC/Inc.
Confirm vendor did not use DBA name
Request updated signed W-9
Confirm correct TIN type (EIN vs SSN)
Validate corrected record with IRS matching
Update vendor master data system
Store documentation for audit trail

Real Examples of TIN/Name Mismatch Fixes

Example 1: Missing LLC Suffix

Submitted:

  • Apex Consulting
  • EIN: 12-3456789

Correct IRS Name:

  • Apex Consulting LLC

Fix: Update vendor name to include "LLC" and revalidate.

Example 2: EIN Typo

Submitted:

  • 55-1234568
    Correct:
  • 55-1234567

Fix: Correct the EIN and revalidate.

Example 3: Contractor Used Nickname

Submitted:

  • Mike Johnson
    SSN: 123-45-6789

IRS record:

  • Michael Johnson

Fix: Update name to legal IRS name and revalidate.

Example 4: Vendor Provided Wrong TIN Type

Submitted:

  • Jane Doe Consulting
    TIN: EIN

IRS expects:

  • Jane Doe + SSN

Fix: Request corrected W-9 and validate correct taxpayer ID type.

What If the Vendor Will Not Provide Correct Information?

If the vendor refuses to provide corrected taxpayer information, businesses may need to:

  • stop onboarding until compliance is met
  • delay payment processing
  • begin backup withholding (if required)
  • document outreach attempts
  • escalate to compliance/legal teams

Vendors who refuse to provide correct taxpayer information create significant reporting risk.

Common Mistakes When Fixing TIN/Name Mismatches

Avoid these common mistakes:

  • accepting corrections without a signed W-9
  • updating the vendor name but not the ERP record
  • confusing DBA name with legal IRS name
  • failing to revalidate after updates
  • waiting until year-end filing season
  • not tracking mismatch history

Many companies fix mismatches temporarily, but do not prevent them from recurring.

How to Prevent TIN/Name Mismatches in the Future

To reduce future mismatches, organizations should implement proactive compliance controls:

Require W-9 completion before issuing payment
Validate vendor name/TIN during onboarding
Revalidate vendors annually before filing season
Standardize vendor naming conventions
Store legal name and tax classification properly
Maintain audit-ready records and validation logs

The best way to fix mismatches is to prevent them from happening in the first place.

Frequently Asked Questions (FAQ)

How do I know if the mismatch is the vendor’s fault or my company’s fault?

It can be either. Many mismatches come from vendor errors, but many are caused by manual data entry issues inside AP or ERP systems.

Can I fix a mismatch without requesting a W-9?

Sometimes. If the issue is a typo or missing suffix, you may be able to correct it internally. However, a signed W-9 is best practice.

What is the fastest way to confirm a mismatch is resolved?

Run IRS TIN matching again after correcting the record.

Will the IRS notify me if there is a mismatch?

Yes, mismatches are often identified after filing and reported through CP2100 notices and B-Notice requirements.

Should mismatches be fixed immediately or at year-end?

Immediately. Waiting until year-end creates significant filing risk and increases the chance of penalties.

Conclusion

Fixing a TIN/name mismatch requires identifying whether the issue is caused by a typo, legal name formatting error, DBA usage, or incorrect taxpayer ID type. The most effective solution is to request an updated W-9, validate the corrected information through IRS TIN matching, and update vendor master data in your ERP system. Organizations that resolve mismatches early reduce CP2100 notices, prevent B-Notices, and avoid costly corrected 1099 filings.

Fix Vendor Mismatches Faster with TIN Comply

TIN Comply helps organizations identify and fix TIN/name mismatches through real-time IRS TIN matching, bulk vendor list validation, and automated vendor outreach workflows. With audit-ready reporting and secure W-9 collection tools, TIN Comply makes it easy to correct vendor records early and prevent compliance issues before filing season.

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