The IRS uses Notice CP2057 to inform you that they have information that was not included on your return & they may want you to file an Amended Return (Form 1040X). See also Letter 6115C.
Respond to Notice CP2057 or Letter 6115C
On the 2nd or 3rd page of the notice the IRS should list the items not included on the return. If it does not appear there you can call the IRS at 1-800-829-1040 & order your Wage & Income Transcripts, which will show all third-party documents filed with the IRS for you.
Often, the IRS records are not wrong, they simply lack additional information to explain or offset the IRS documentation. And, because you may file an amended return you have the opportunity to discover more deductions or credits to claim on the new return. So, use the Form 1040x to respond to the IRS Notice CP2057 and also to make further claims if possible.
Please follow the Notice CP2057 Return Error Prep Steps for guidance to contest this IRS notice. The attorney will construct an Action Plan for you to fight the IRS!