Social Security Number (SSN): What It Means for Employers

What it means in practice

What an SSN is. The IRS describes taxpayer identification numbers as numbers used to administer the tax laws, issued either by SSA or by the IRS; the SSN is the one SSA issues. The General Instructions for Forms W-2 and W-3 explain that the IRS uses SSNs to check the payments an employer reports against employees' tax returns, and SSA uses them to record employees' earnings for future Social Security and Medicare benefits. For the agency itself, see Social Security Administration.

The employer's basic duty. Section 4 of Publication 15 (2026) says you are required to get each employee's name and SSN and enter them on Form W-2, including for resident and nonresident alien employees. You should ask to see the Social Security card, but the employee is not required to show it if it is not available; you should then verify the SSN and the employee's eligibility for employment. Photocopying the card is optional. Do not accept a card that says "Not valid for employment." The regulation at 26 CFR 31.6011(b)-2(c) says the employer enters the number and name exactly as shown on the card in its records, returns and employee statements.

Asking for the number. IRS Publication 1586 (Rev. 8-2026) says an employer must make an initial solicitation for the SSN when the employee begins work, in person, orally or in writing, and may rely in good faith on the number the employee gives. Because a new employee must provide a signed Form W-4, the W-4 may serve as that solicitation, and keeping it documents that the employer acted responsibly. Step 1 of the 2026 Form W-4 asks for the SSN.

Step by step at hire. (1) Ask for the name and SSN, normally through Form W-4, and ask to see the card. (2) Record both exactly as on the card. (3) Reject any card marked "Not valid for employment" and any ITIN. (4) If there is no number yet, follow the applied-for rules below. (5) Optionally verify through SSNVS. (6) Keep the record with your employment tax records. Employment eligibility is a separate step on Form I-9; see onboarding for the full sequence.

Employees without an SSN. Publication 15 says an employee legally eligible to work who has no card can apply on Form SS-5; the employee must complete and sign it, and the employer cannot file it. Under 26 CFR 31.6011(b)-2(a)(2), the employee files Form SS-5 on or before the seventh day after starting work. If the employee shows an SSA receipt for the application, the regulation tells the employer to record the name and address exactly as on the receipt, its expiration date and the issuing office's address. If the number has not arrived when Form W-2 is due, the W-2 instructions say to enter "Applied For" in box a on paper, or zeros if e-filing (000-00-0000 online, 000000000 in an uploaded file), then file Form W-2c once the employee reports the number. USCIS says such employees may work while awaiting their SSN.

Recording the name exactly. The W-2 instructions say to enter the name as shown on the card and call the exact last name especially important. Separate parts of a compound name with a hyphen or space, never join them, and leave off titles such as "Dr." or "Esq." Generally omit suffixes such as "Jr." on Copy A unless shown on the card. After a name change, Publication 15 says the employee should request an updated card, and you keep reporting under the old name until shown the new card.

Verifying SSNs. Publication 15 says employers and authorized reporting agents can use SSNVS to check that a name matches an SSN, instantly for up to 10 at a time or by file upload of up to 250,000. SSNVS is reached through SSA's Business Services Online (BSO), which needs a Social Security online account using a Login.gov or ID.me credential; the W-2 instructions call these free services. Publication 1586 says the IRS does not require their use. Publication 15 cautions that a person may have a valid SSN but not be authorized to work in the United States.

Name and SSN mismatches. Publication 1586 says SSA and IRS databases are not identical, and IRS penalty notices about mismatched numbers come only from IRS systems. A mismatch reported through SSA verification is not an IRS notice and does not trigger further solicitation requirements under IRS reasonable cause rules, though the employer may wish to re-solicit the SSN before filing Form W-2. Once the IRS notifies an employer of an incorrect number by penalty notice (Notice 972CG), Publication 1586 requires an annual solicitation by December 31 of that year (January 31 if notified in December); Form W-4 may be used for it.

ITINs are not SSNs. Publication 15 says not to accept an Individual Taxpayer Identification Number in place of an SSN for employee identification or for work. ITINs go only to aliens not eligible for U.S. employment who need a number for other tax purposes. They start with 9 and have 50-65, 70-88, 90-92 or 94-99 as the fourth and fifth digits. The W-2 instructions warn not to auto-populate an ITIN into box a. The IRS ITIN page says an ITIN does not authorize work and a person cannot hold both numbers; someone who becomes eligible to work must obtain an SSN.

How the SSN relates to Form I-9. The USCIS Handbook for Employers (M-274), section 3.0, says employees may voluntarily provide their SSN in Section 1 of Form I-9 or leave it blank, but employees of employers enrolled in E-Verify must provide it. USCIS also says you cannot ask employees for a specific document with their SSN on it, which may constitute unlawful discrimination. Which documents an employee presents is covered under Form I-9. E-Verify compares Form I-9 information against DHS and SSA records.

Truncation and privacy. The W-2 instructions let employers replace the first five digits with asterisks or Xs (XXX-XX-1234) on employee copies of Form W-2. Truncation is voluntary and never allowed on Copy A of Forms W-2 or W-2c; e-filed W-2s must carry the complete SSN. Under 26 CFR 301.6109-4, permitted truncation does not trigger a payee statement penalty, but an employer may never truncate its own EIN. The FTC's guide Protecting Personal Information tells businesses to use SSNs only for required and lawful purposes, like reporting employee taxes, and not as an employee identification number. See also payroll security.

Correcting a name or SSN. The W-2 instructions say to correct an incorrect name or SSN on a filed Form W-2 with Form W-2c, filing Copy A with SSA and a Form W-3c every time. When correcting only the name or SSN, complete boxes d through i, not boxes 1 through 20: box d shows the correct SSN, box f the previously reported SSN (zeros if blank), box g the name as previously reported. If both SSN and name were reported blank, do not use Form W-2c; contact SSA at 800-772-6270. After a new card for a name change or change in alien work status, correct only the most recently filed Form W-2. Errors caught before Copy A reaches SSA are handled by marking it "VOID" and issuing a new W-2.

Penalties. The W-2 instructions say the section 6721 penalty can apply when you report an incorrect TIN or fail to report one, unless you show reasonable cause. For Forms W-2 due after December 31, 2026, it is $60 per form if corrected within 30 days after the due date, $130 if corrected by August 1, and $340 after that or if never corrected, subject to annual maximums, and at least $690 per form for intentional disregard. TIN and surname errors are never inconsequential. A de minimis rule excuses the greater of 10 returns or one-half of 1% of returns filed on time and corrected by August 1. The section 6722 penalty for incorrect payee statements is additional, in the same amounts.

Recordkeeping. Publication 15 says to keep employment tax records for at least 4 years, including employees' names, addresses, SSNs and occupations, and copies of their Forms W-4.

Example 1 (illustration): number pending at year end. A worker hired in November 2026 shows an SSA receipt for a pending application, and the employer records the name and address as on the receipt. The number has not arrived when 2026 Forms W-2 are e-filed, so box a shows 000000000. When the card arrives in March 2027, the employer files Forms W-2c and W-3c with the SSN in box d and zeros in box f.

Example 2 (illustration): penalty arithmetic. An employer timely files 2026 Forms W-2 that, with its other information returns, total 400 returns. Twelve show transposed SSNs, all corrected within 30 days of the due date. Without reasonable cause, the de minimis rule covers the greater of 10 or 2 (0.5% of 400) returns, leaving 2 x $60 = $120 under section 6721, before any separate section 6722 amount.

Example 3 (illustration): name change. An employee marries in June 2026 and asks payroll to use a new surname. Until the employee shows an updated card, wages stay reported under the name on the existing card. If the updated card arrives after the 2026 Form W-2 is filed, the employer corrects only that most recent Form W-2 with a W-2c.

Where states differ. The W-2 instructions tell employers to check with state, local or territorial governments on whether truncated SSNs are allowed on W-2 copies submitted to them. Pay statements are another example: the California Labor Commissioner's FAQ on paydays says that since January 1, 2008, only the last four digits of the SSN, or an employee identification number other than an SSN, may be shown on the itemized wage statement (Labor Code section 226(a)(7)).

Question: Must an employee show the Social Security card? Publication 15 says you should ask, but the employee is not required to show it if unavailable; you should then verify the SSN and employment eligibility.

Question: Do I have to use SSNVS? No. Publication 1586 says there is no IRS requirement to use SSA's verification systems, though they help catch mismatches before penalty notices.

Question: Can a new hire use an ITIN until an SSN arrives? No. Publication 15 says an ITIN is never accepted in place of an SSN; use the "Applied For" or zeros rule instead.

Question: Do I need a W-2c for every past year after a name change? No. Only the most recently filed Form W-2 needs correction if the prior name and number were used for earlier years (Publication 15).

This entry describes federal rules and one state example and does not decide whether a particular employee, document or filing is correct.

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