An IRS officer is a civil agency employee of the Internal Revenue Service (IRS) whose duties include collecting taxes that are delinquent and have not been paid to the IRS, securing tax returns that are overdue from businesses and individuals, and helping taxpayers resolve their account balances. There are two types of IRS officers: Revenue Agents and Revenue Officers.

• Revenue Agents: Their job is to conduct tax audits of individuals, businesses, trusts, and non-profit organizations. Revenue agents generally conduct tax audits of the most complicated tax returns ranging from small "Schedule C" businesses to the largest multi-national corporations. They determine tax liability through a tax audit, which is sometimes referred to as an examination. Revenue Agents do not collect tax. Instead, that task falls to an IRS Revenue Officer.

• Revenue Officers: They are assigned to the most difficult IRS tax debt cases. These are individuals or businesses who the IRS has been unable to collect from through letters, phone calls, and tax levies and garnishments generated by IRS computers. Revenue Officers are not generally accountants and they have little training in substantive law. Therefore, statements to revenue officers that the tax is not owed generally dont get very far. The IRS describes the Revenue Officers job as follows: "The role of the Revenue Officer is to collect taxes that are delinquent and have not been paid to the IRS and to secure tax returns that are overdue from businesses and individuals".

Revenue Officers are specially trained to collect taxes owed, and with their absolute collections authority, these officers are permitted to act in ways that typical IRS personnel are not. They are caseworkers who will be assigned to a case if a taxpayer owes back taxes exceeding $100,000. Before being contacted by a Revenue Officer, taxpayers should first receive information regarding their tax bill in the mail and a deadline by which they should pay, appeal, or negotiate a settlement.