If you file W-2s or 1099s for employees or contractors, there are several other IRS letters you might receive. Each serves a different purpose. If you do get a letter from the IRS, locate any of these codes in the top right corner of the letter, and you’ll be able to quickly identify the reason for the IRS alert(s).
- CP2100 / CP2100A 
 Alerts you that a payee’s name and TIN (Taxpayer Identification Number) don’t match IRS records. You may need to send a B Notice and begin backup withholding.
- CP215 / CP2501C 
 Notifies you of a proposed penalty for late, incorrect, or missing filings. You can respond to dispute or pay the penalty.
- Letter 972CG 
 Informs you of penalties for late or incorrect 1099/W-2 submissions. You typically have 45 days to respond or appeal.
- Letter 5005-A / 5005-B 
 Identifies backup withholding issues due to incorrect payee information. Similar to CP2100, it may require B Notices and withholding.
- Letter 226J 
 Sent to Applicable Large Employers (ALEs) under the Affordable Care Act. It indicates a potential penalty if W-2 data suggests you didn’t offer qualifying health coverage.
- Letter 1948C 
 Requests clarification about the filing status of certain 1099s or W-2s due to inconsistencies.
🧾 Letters Related to Filing Methods or Corrections
- CP136 
 A reminder to deposit backup withholding or other federal income taxes related to 1099/W-2 payments.
- CP148A 
 Confirms that the IRS has updated its records based on name/TIN corrections you submitted.
✅ What You Can Do
- Double-check names and TINs before submitting W-2s or 1099s. 
- If you receive a CP2100, review the affected forms and respond promptly. 
- Only respond to Letter 1865C if the IRS asks for additional information. 
- Keep all tax-related correspondence and documentation for at least four years. 
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