Tax audits that the IRS performs by mail. Correspondence audits are the lowest level of auditng performed by the IRS. The IRS sends the taxpayer a written request for additional information about a specific item or issue on a specific tax return. If the taxpayer can produce sufficient evidence to resolve the issue, the procedure is closed. A correspondence audit is considered the least serious form of an audit because it is generally only used for relatively simple matters and involves small amounts of momey. The next step after a correspondence audit is an office audit, where the IRS requires the taxpayer to come to an IRS location to discuss the issue in question.