IRS, the /ˌaɪ ɑːr ˈes/ BrE AmE
abbreviation for the Internal Revenue Service; the government organization in the US which is responsible for collecting national taxes, especially ↑ income tax (based on how much money you earn) and CORPORATION TAX (based on how much profit a company makes). People in the US have to send an INCOME TAX RETURN by April every year (=an official form showing how much tax they have paid and how much they owe) .