The IRS conducts audits to verify income, deductions, expenses, and credits claimed on tax returns. Here's what to do if you receive a letter that says the IRS is auditing your tax return by mail. First, read the letter carefully. It explains the issues involved and outlines the types of information you need to send us. We'll ask for documents to support information on your tax return. If you're not able to verify something, you'll need to explain how you determined the amount you reported. There are different ways you can submit the information to us. Regardless of how you submit it, you should always include the reply coversheet with the documents you send. Here are the options for submitting information to the IRS: One, the document upload tool. This is a secure and convenient way to upload your correspondence. The notice will tell you how to share your documents with us online. Two, fax. If you prefer to fax, use the number provided in the letter you received. Three, postal mail. If you mail your information, use the envelope provided. If your information doesn't fit, you can use your own envelope. Do not mail original documents when you submit your information. No matter how you submit your information, remember to keep copies of everything you send us. In addition to these three options, some letters may include an invitation to use the taxpayer digital communication option. If you receive this invitation, we encourage you to use this option to submit your documents through secure messaging. You'll find instructions for signing up in your invitation. Be sure to send your documents to us by the deadline shown in your letter. If you can't meet this deadline, you can request an extension by mailing or faxing us your request, or by calling the number on the letter to ask for additional time. If we determine the documents you sent are sufficient, we'll close your case and send you a letter to let you know that there's nothing else to do. If we determine that the documentation is insufficient, we will send you a letter to let you know what information we still need to resolve your case. If you agree with our proposed changes, follow the instructions in your letter to have your case closed. If you disagree with the proposed changes, send us an explanation with your supporting documents. Remember, you have the right to request an appeal review with the IRS. If you disagree with the proposed changes, and don't request an appeal review, you'll receive a certified statutory notice of deficiency. You can continue to work with us by providing the requested information to resolve your examination, or you can follow the instructions in the letter to petition tax court. For more information about audits, go to IRS.gov/audit. You can also refer to publication 3498-a included with your letter.