IRS Notice CP 21B - Data Processing Adjustment Notice, Overpayment of $1 or More

This is not a bill - the IRS has made changes you requested to your tax return and there was an overpayment based on this adjustment. You will be receiving an additional tax refund within 2-3 weeks of the notice.

The notice explains the changes to the tax return.

If you agree with the adjustment(s) make the appropriate changes to your tax return record. If you do not agree with the change, call or write to the IRS at the phone number or address given in the header section of the notice.

Sections of the Notice:

  • Header Section
    This area contains the Notice Number, the applicable tax year, the notice date, your Social Security Number, and the IRS contact number.
  • Explanation Section
    This section explains the reasons for the changes to your return and provides information on what you should do.
  • Response Section
    If you have questions or do not agree with the adjustment, the notice directs you to contact the IRS at the number listed in the header section.


Sample CP 21B: