Social Security Number (SSN)
A Social Security Number (SSN) is a 9-digit number issued to U.S. citizens, permanent residents, and foreign nationals authorized to work in the United States. You need an SSN to get a job, collect Social Security benefits, pay taxes, and receive some government services. If you’re a foreign national working temporarily in the U.S., your employer will require your SSN.
Employer Identification Number (EIN)
An Employer Identification Number (EIN) is a 9-digit number used to identify tax accounts for businesses and certain entities operating in the U.S. You need an EIN if you have employees, operate your business as a corporation or partnership, or file any of several business tax returns. You don’t need an SSN or ITIN to get an EIN.
Individual Taxpayer Identification Number (ITIN)
An Individual Taxpayer Identification Number (ITIN) is a 9-digit number issued by the IRS to foreign nationals and others not eligible for an SSN. You need an ITIN to pay taxes if you earn income in the U.S. and are not eligible for an SSN.
Foreign students and scholars can obtain SSNs if they have authorization to work in the U.S. They need to apply in person and provide original immigration documents as proof of work authorization. Those not eligible for an SSN can file taxes with an ITIN.