What Employers Need To Know About Social Security

Manager going over new employee paperwork

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In general, anyone who wants to legally work in the U.S. needs a Social Security number (SSN). Businesses that hire employees need to know about these numbers because they are needed for several identification and verification purposes. SSNs are also used by two types of single-owner businesses for business tax identification purposes.

This article gives details on SSNs for employers and sole proprietors so they can comply with Internal Revenue Service (IRS) and Social Security Administration (SSA) regulations.

Social Security Numbers vs. Tax ID Numbers

A Social Security number (SSN) is just one form of taxpayer ID number. An employee may have one of several other identifiers:

SSNs for Single-Owner Businesses

Most business types need an EIN, but sole proprietorships use the owner's SSN as their business identifier because this business type isn't considered separate from the owner. A one-owner limited liability company (LLC), which is normally taxed like a sole proprietorship, can also use the owner's Social Security number as the business identifier in most cases.

Sole proprietors and single-member LLCs must use an EIN, not their SSN, if the business has employees or it must pay excise taxes.

SSNs for Employee Verification

New employees may need SSNs to verify that they are eligible to work in the U.S. and for federal tax purposes.

Work Verification for Immigration Purposes

Employers must use Form I-9 from the U.S. Citizenship and Immigration Service to verify employee identity and their authorization to work in the U.S. Social Security cards are just one type of documentation for this purpose.

A new hire can use a Social Security card or another type of document (Class B document) to verify employment authorization. They must also provide another document (Class C document), to establish identity. A Social Security card doesn't have a photo on it, so there's no way to verify identity with this card. You must examine the documents and note on Form I-9 which documents you looked at.


If the person gives you a Social Security card, look at it carefully. The card must be unrestricted, meaning it can't have restrictive wording on it, like "NOT VALID FOR EMPLOYMENT," "VALID FOR WORK ONLY WITH INS AUTHORIZATION" or "VALID FOR WORK ONLY WITH DHS AUTHORIZATION."

Work Identification for Tax Purposes

All new hires must complete Form W-4 before receiving their first paycheck, and they must include their SSN on the form. The IRS does not allow employers to accept an individual tax identification number (ITIN) for employee work identification. An ITIN is used only for tax processing purposes for certain individuals who can't get an SSN.


By tax law, you must enter a correct SSN on each employee's W-2 form to report their taxable income for the year. Employees enter this number on Form W-4, so be sure you copy it correctly to the W-2 form. You may be subject to a penalty for incorrect or missing employee SSNs.

Employer Correction Request Letters

Employers sometimes receive a letter in the mail called an Employer Correction Request for missing or incorrect SSNs from the Social Security Administration. The information may have been given incorrectly by the employee on their W-4 form or it was entered incorrectly on the W-2 form.

Don't take any action against the employee. Laying off, suspending, firing, or discriminating against the employee could be a violation of state or federal law.

To correct the error, you'll need to register with the Social Security Administration's Business Services Online system. Then follow the instructions in the letter to make the correction.


For more information on error correction letters from the Social Security Administration, see this document with "Questions Employers Ask" and this webpage with sample error correction request notices.

Frequently Asked Questions (FAQs)

How can I verify an employee's Social Security number?

You can verify an employee's SSN by signing up for SSN Verification through the SSA's Business Services Online portal. You can also use the portal to correct any errors. It can only be used to verify current or former employees and only for wage reporting (Form W-2).

Can an employer require a Social Security card?

For verification of employee work eligibility for Form I-9, the Social Security card isn't required specifically. It's just one in a list of possible forms of verification.

For use on the employee's W-4 form for tax withholding, an SSNN is required. The employee isn't required to show you their Social Security card. If the employee shows you their card, you can copy it for your records.

Can I hire someone who doesn't have a Social Security number?

It's legal to hire someone who claims not to have a Social Security card or who doesn't remember their SSN, but you as the employer are legally liable if the SSN on the employee's W-2 form is incorrect or missing.

Urge the person to apply for an SSN or replacement Social Security card as soon as possible using SSA Form SS-5.

How do I know if a card is a social security card or an ITIN?

The ITIN is a nine-digit number formatted like the SSN. An ITIN will start with the number "9" and have a range of numbers from “50– 65,” “70–88,” “90–92,” and “94–99” for the fourth and fifth digits.

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The Balance uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. IRS. "Single Member Limited Liability Companies." Accessed July 27, 2021.

  2. U.S. Citizenship and Immigration Services. "Form I-9 Acceptable Documents." Accessed July 27, 2021.

  3. IRS. "Publication 15 (Circular E) Employer's Tax Guide." Page 15. Accessed July 27, 2021.

  4. Social Security Administration. "The Social Security Number Verification Service." Accessed July 27, 2021.

  5. Texas Workforce Commission. "Employees Without Social Security Numbers." Accessed July 27, 2021.

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