The CP12 Notice is sent when:

• The IRS found a math or clerical error on your return
• They made a correction
• The change results in a refund amount different from what you claimed — or it eliminates the tax you thought you owed

Your notice will outline:

• What you originally claimed as your refund or owed amount
• The IRS's corrected figure
• When you can expect the refund (if applicable)
• The specific error they identified and corrected

Common triggers for a CP12 include:

Calculation Errors:

• Miscalculating a credit like the Earned Income Tax Credit or Child Tax Credit
• Overstating withholding or estimated tax payments
• Incorrectly entering income figures that change your refund calculation
• Simple addition or subtraction errors
• Incorrect calculation of self-employment tax

Reporting Errors:

• Missing or incorrect Social Security numbers
• Filing status errors that affect tax calculations
• Dependent eligibility issues
• Income reporting discrepancies with IRS records

Step 1: Read the Notice Thoroughly
Make sure you understand what the IRS changed and why. Compare their changes with your original tax return.

Step 2: Decide if You Agree

• If you agree: No action is needed. The IRS will send your adjusted refund within 4-6 weeks
• If you disagree: Contact the IRS immediately — you generally have 60 days from the date of the notice to dispute it

Step 3: Keep the Notice for Your Records
Even if you agree, store this notice with your tax documents for at least three years.

If You Disagree with the Changes:

• Call the IRS at the number provided on the notice
• Have your notice, tax return, and supporting documents ready
• Clearly explain why you believe the original return was correct
• Follow up in writing if instructed to do so
• Keep records of all communications with the IRS

If You Agree with the Changes:

• Nothing bad happens — you'll just receive the adjusted refund
• The IRS will process your return with their corrections
• Your tax account will be updated to reflect the changes

If You Disagree and Ignore It:

• You could lose your right to appeal the changes
• The IRS will process the return with their corrections
• You may end up with an incorrect return on file
• Future discrepancies may arise from the incorrect filing
• You may need to file an amended return to correct their "correction"

Preparation and Filing Tips:

• Double-check math before filing — use tax software or a calculator
• Verify eligibility for all tax credits and deductions
• Keep records of all income and withholding documents
• Use a trusted tax preparer to reduce the chance of clerical errors
• Review your return carefully before submitting it

Documentation Practices:

• Keep copies of all W-2s, 1099s, and other income statements
• Maintain records of estimated tax payments and withholding
• Save documentation for credits and deductions claimed
• Organize your tax documents throughout the year

Technology Solutions:

• Use reputable tax preparation software with error-checking features
• E-file your return to reduce transcription errors
• Set up direct deposit for refunds to avoid check errors
• Use the IRS withholding calculator to ensure proper withholding