The IRS sends Notice CP60 to tell you they are adjusting your account for miscalculations, erroneous positions or IRS mistakes. Therefore, look carefully at your tax return and the IRS notice to see any discrepancy in the credits claimed.
Respond to Notice CP60
It may be hard to discern from the Notice CP60 exactly why the IRS has made adjustments. The usual explanation is that a penalty has been abated but you still owe. Therefore, it would be best to call the IRS at 1-800-829-1040 obtain your Account Transcripts & see what payments & changes have occurred on your account. You may have to get the Taxpayer Advocate involved to figure it out.