Let the IRS know of a disputed notice. Send a typewritten letter to the IRS office that sent the notice.Use the format in the sample letter below. In this article, we will provide you with a detailed guide on the steps involved in writing a letter to the IRS. Substitute IRS Form W-9. Request for Taxpayer Identification Number and Certification. Sending an IRS audit reconsideration request? To change your EIN status from a Partnership to a Single Member LLC, you must write or FAX a letter to the IRS facility where you originally filed your EIN. In the first paragraph of your letter, explain why you are writing the IRS. Mention the date of their notice.