The three types of IRS audits are mail audits, field audits and office audits 1. Mail audits: The IRS requests specific information, through mail correspondence, to support items on a business’s tax return. 2. Field audits: This in-person audit takes place at the business, where an IRS agent reviews records and asks questions about the tax return. 3. Office audits: The IRS asks the business owner to come to an IRS office to provide documentation that supports items on its tax return.