The Identity Protection PIN is a six-digit number assigned to eligible taxpayers and is known only to the taxpayer and the IRS. It helps prevent identity thieves from filing fraudulent tax returns using a taxpayer’s Social Security number. IR-2021-09, January 12, 2021 — All taxpayers now eligible for Identity Protection PINs IR-2021-09SP, January 12, 2021 — Todos los contribuyentes ahora son elegibles para PIN de Protección de Identidad | Internal Revenue Service (irs.gov)