The IRS has adjusted your tax return and these changes affect your refund.
The notice explains the changes to the tax return and the amount of the overpayment that was applied to your tax balance from prior year returns.
If you agree with the adjustment, make the changes to your tax return records to reflect the IRS adjustment. 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:
Sample CP 16: PDF Pages 1-3
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.