no way to tell from what little you provided. what does it say to do?
What is the number after CP or LTR in the upper right hand corner of the notice ? Did you file a return ? Was it frivolous ?
The IRS does issue a 3176C letter for returns that they deem are incorrect or which are filed and are not in accordance with the tax laws.
Please see the excerpt below from the IRS website on the their treatment for various types of returns they consider as frivolous. These procedures are in place to prevent fraud and assess penalties should the IRS determine a frivolous tax return was filed.
When the IRS issues this letter, they will also provide you with a timeline to respond to their notice allowing you provide information that supports your return.