Form SS-4 2026: How to Apply for an EIN (Employer Identification Number) — Complete Guide
Form SS-4 is the official IRS application for an Employer Identification Number (EIN) — the 9-digit federal tax ID every U.S. business needs. This complete 2026 guide covers who needs an EIN, how to fill out Form SS-4 line by line, all three application methods, processing times, and common mistakes to avoid.