Use Form SS-4 to apply for an employer identification number (EIN). An EIN is a 9-digit number (for example, 12-3456789) assigned to employers, sole proprietors, corporations, partnerships, estates, trusts, certain individuals, and other entities for tax filing and reporting purposes. Note: Keep the Form SS-4 information current. Use Form 8822-B to report changes to your responsible party, address or location. Changes in responsible parties must be reported to the IRS within 60 days. Current revision Form SS-4 PDF Instructions for Form SS-4 (Print Version) PDF Recent developments Reinstatement of Form SS-4’s line 14 election to file Form 944 annually -- 28-MAR-2024 Certain forms, instructions, and publications used by taxpayers in Puerto Rico have been replaced -- 14-MAR-2024 Other items you may find useful All Form SS-4 revisions Apply for an employer identification number (EIN) online About Publication 15 (Circular E), Employer's Tax Guide About Publication 51 (Circular A), Agricultural Employer's Tax Guide About Publication 80, Federal Tax Guide for Employers in the U.S. Virgin Islands, Guam, American Samoa, and the Commonwealth of the Northern Mariana Islands Other current products Related items About Form 11-C, Occupational Tax and Registration Return for Wagering About Form 637, Application for Registration (For Certain Excise Tax Activities) About Form 720, Quarterly Federal Excise Tax Return About Form 944, Employer's Annual Federal Tax Return About Form 990-T, Exempt Organization Business Income Tax Return (and proxy tax under section 6033(e)) About Form SS-4 (PR), Application for Employer Identification Number (EIN) (Puerto Rican Version)