Common W-2 Errors That Require a W-2C for 2026

Common W-2 Errors That Require Form W-2C

Even with careful preparation, errors on W-2 forms can occur. Understanding the most common mistakes helps you avoid them and know when a Form W-2C correction is required.

For detailed instructions on completing Form W-2C, see our W-2C box instructions guide.

Employee Name and SSN Errors

These are among the most common errors and often trigger SSA rejection notices:

• Incorrect Social Security Number: Transposed digits, typos, or using an old SSN
• Name mismatch: The name on the W-2 does not match SSA records
• Legal name changes: Employee married or divorced and SSA records were not updated
• Suffix errors: Jr., Sr., III, etc. included or excluded incorrectly

Tip: Always verify employee SSNs match their Social Security cards before filing.

Wage and Tax Amount Errors

Mathematical or data entry mistakes in wage and tax boxes:

• Transposed amounts: $12,345 entered as $12,435
• Decimal point errors: $1,234.50 entered as $123.45 or $123,450
• Wrong box placement: Amount entered in wrong box (e.g., Box 1 vs Box 3)
• Missing amounts: Forgetting to include certain compensation or deductions
• Calculation errors: Withholding does not match wage amounts

Box 12 Code Errors

Box 12 codes are frequently entered incorrectly:

• Wrong code: Using Code D instead of Code E for 403(b) contributions
• Missing codes: Forgetting to report employer health insurance (Code DD)
• Incorrect amounts: Wrong retirement contribution or benefit amounts
• Duplicate entries: Same code entered multiple times in error

Common Box 12 codes include: C (group-term life insurance), D (401k), DD (employer health coverage cost), E (403b), G (457b), W (HSA contributions).

Box 13 Checkbox Errors

The three checkboxes in Box 13 are often mismarked:

• Statutory employee: Incorrectly checked for regular employees
• Retirement plan: Not checked when employee was eligible for a plan
• Third-party sick pay: Marked when payer is the employer, not a third party

Employer Information Errors

• Wrong EIN: Using an old or incorrect Employer Identification Number
• Business name mismatch: Name does not match IRS records for the EIN
• Address errors: Old address or formatting issues
• State ID number: Wrong or missing state employer identification

State and Local Tax Errors

• Wrong state code: Using incorrect two-letter state abbreviation
• Multi-state allocation: Incorrect wage allocation for employees working in multiple states
• Local tax omissions: Forgetting to report local income tax where required
• Locality name: Misspelled or incorrect local jurisdiction name

When NOT to File W-2C

A W-2C is not required for:

• Address changes (employee can update the IRS directly)
• Errors discovered before the original W-2 was filed with SSA
• Rounding differences of a few cents

Preventing Errors

Best practices to avoid W-2 mistakes:

• Verify employee data: Confirm SSN and legal name before year-end
• Use e-file: Electronic filing includes built-in validation
• Review before submitting: Double-check all amounts and codes
• Keep records: Maintain documentation for all W-2 entries

E-File Form W-2C with BoomTax

E-file your Form W-2C with the SSA using BoomTax. Our platform validates your corrections before submission to help prevent additional errors.

External Resources

• IRS: About Form W-2C
• IRS: Instructions for Forms W-2C and W-3C (PDF)

Frequently Asked Questions About W-2 Corrections