You can find the CP or LTR number on the right corner of the letter. Step One: Provide a request letter to IRS, including the following information: Step Two: Sample Letter to the IRS Date:Keep this notice for your records. We're required to send a copy of this notice to both you and your spouse. We have provided sample letters that you can use to request waivers of several different types of IRS penalties. Most of our letters provide specific instructions of what you need to do. The primary letter we use to request information about a return is Form DTF948 or DTF948O, Request for Information (RFI). Read the letter carefully. Most IRS letters and notices are about federal tax returns or tax accounts. You may request a tax clearance letter for all tax types including individuals and sole proprietors through Georgia Tax Center (GTC).