Internal Revenue Service Internal Revenue Service Internal Revenue Service Servicio de Impuestos Internos Servicio de Impuestos Internos Service des impôts internes השירות הפנימי להכנסות आंतरिक राजस्व सेवा 内国歳入庁 Serviço de Receita Interna 国内税收局 IRS The Internal Revenue Service (IRS) is the revenue service of the United States federal government. The government agency is a bureau of the Department of the Treasury.