"Could it be a scam?"
A real IRS letter will have the IRS logo on the envelope. It will also have a notice number (CP) or a letter number (LTR) in the upper or lower right hand corner. It will also have your partial tax ID number. If in doubt, call the IRS at 800-829-1040.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
