This notice is issued to inform the taxpayer that the IRS has made changes to their return which results in an adjusted overpayment that will be refunded within 4 to 6 weeks if no other taxes or past due debts are owed.
Note. Generally, when an IRS notice is received, the IRS prefers you do NOT file an amended return. Depending on your response (agree, disagree, or partially disagree), the IRS will update their records accordingly. You simply need to print a revised return for your own records.
Sample CP 12: 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.