I received a letter from the IRS. What do I do?

The first thing to do is not to panic. Many notices can be cleared up with a simple phone call or submission of some documents. Many times the IRS is wrong in their calculations or there is a misunderstanding. You need to be responsive by contacting the IRS on a timely basis. Usually you have 30 days from the date of the notice. They take it as a sign of disrespect if they don't hear from you. I recommend that you give the notice to your CPA to handle.