The first thing is not to worry much. Each year, thousands of taxpayers receive mail from the IRS for various reasons. Read the letter carefully; not every IRS letter is bad news. The IRS also sends letters for reasons such as ID verification, additional information, or changes in your return. Do not reply to the letter unless you are instructed to do so. Act promptly if a deadline is mentioned in the letter. Contact your IRS agent if you need more information.