Hi, I'm Patti, and I work for the IRS. We conduct many types of audits each year to verify income and expenses claimed on tax returns. Many of these audits are conducted by mail. So, what do you do if you receive a letter that says the IRS is auditing your tax return by mail? First, be sure to read your letter carefully. The letter explains the issues involved and outlines the types of information you need to send to us. We may ask for an itemized list of the expenses or deductions in question. If you're not able to verify an amount claimed, just explain the issue and how you determined the amount reported on your tax return. After you've collected the requested information, attach photocopies of your documents to the audit letter you received. Use the envelope enclosed with your letter to send the information back to us. However, if your documents don't fit in the envelope, send us the information by using the address on the envelope. Don't send original documents, and it is always a good idea to keep copies of everything you send. Your letter has a fax number if you prefer to fax your information. But, if you're faxing your documents, include your name and Social Security number on each page to ensure all pages are associated with your case file. Be sure to send your documents to us within 30 days. If you can't meet the deadline, call the number on the letter to discuss your situation and request additional time. After we receive your information, we'll review it. Then, you'll get another letter accepting your information or proposing changes to your tax return. If we propose changes to your tax return, this letter will also include two forms. Form 4549, Income Tax Examination Changes, which explains the proposed changes to your tax return, and Form 886-A, Explanation of Items, which describes the specific changes and reasons for them. If you understand and agree with the proposed changes, sign and date the Form 4549. Use the envelope we provided to return the form with your payment. If you disagree with the proposed changes, you have the right to appeal both within the IRS and before the courts. An explanation of how to appeal is included in the letter. Also, Publication 3498-A, The Examination Process (Audits by Mail), is available on our website, IRS.gov. This publication tells you what you need to do and explains your responsibilities and rights during and after an audit. Meanwhile, our website has information about what to do if you owe additional taxes, such as paying your tax bill or applying for an online payment plan. Remember, if you pay your bill in full, you'll reduce the amount of interest and penalties you will owe. For more information about audits, go to IRS.gov and type "audit" in the search field.