Why certified payroll uses an identifying number, not a Social Security number

Certified payrolls are handled by a lot of people. They pass from a sub to a prime to an agency, sit on shared drives and in portals, and are subject to Freedom of Information Act requests. For years they carried every worker's full Social Security number and home address, and identity theft from stolen payrolls was a documented problem. The Department of Labor amended the regulation in December 2008, effective January 2009, and reissued the form to match.

What the regulation says

The certified payroll clause, 29 CFR 5.5(a)(3)(ii)(B), is direct: "full Social Security numbers and last known addresses, telephone numbers, and email addresses must not be included on weekly transmittals. Instead, the certified payrolls need only include an individually identifying number for each worker (e.g., the last four digits of the worker's Social Security number)."

Two things follow. Putting a full SSN on the WH-347 violates the clause. And the identifying number is yours to choose, as long as it identifies the worker consistently.

What to use

The last 4 digits of the SSN. The regulation's own example and the most common choice. It is stable, the worker knows it, and it matches what many payroll systems print on stubs.

An employee number. Whatever your payroll system assigns. This has an advantage the last-4 does not: it contains no part of the SSN, so a leaked payroll leaks nothing sensitive. It is also what the Department's form instructions contemplate when they say "individual identifying number (e.g., last four digits of SSN)"; the example is an example.

Whichever you pick, use the same number for the same worker on every payroll and every project. Reviewers match workers week to week by name and number, and a worker who is "6789" one week and "E-1041" the next looks like 2 people.

What stays in your records

The privacy rule applies to what you send. Your own payroll records must still contain each worker's full Social Security number and last known address, telephone number, and email address, kept for 3 years after the prime contract is complete. The Department needs them to reach workers who are owed back wages. The retention rules.

What the government can ask for

The same clause requires you to hand over the full details when an investigation needs them: contractors "must provide them upon request" to the contracting agency or the Wage and Hour Division, or, where a federal agency is not a party to the contract, to the applicant, sponsor, or owner for transmission. The rule is privacy in transit, not secrecy from the government.

What the prime can ask for

The clause anticipates that a prime contractor may want the full information for its own files, and allows it: it is not a violation for a prime "to require a subcontractor to provide full Social Security numbers and last known addresses, telephone numbers, and email addresses to the prime contractor for its own records, without weekly submission by the subcontractor to the sponsoring government agency."

So a prime may send you a one-time worker information form and ask for full SSNs. You can comply. What the prime may not do is require you to print them on the weekly WH-347, and what you should not do is email a spreadsheet of full SSNs without encryption because someone asked.

The 2025 form

The January 2025 revision of the WH-347 labels the field "Worker identifying no." in column 1E and the instructions repeat that "workers' full Social Security numbers must not be included." The form has had no address field since 2009.

State forms are a different story

State prevailing wage laws set their own recordkeeping and reporting rules, and several still require the data the federal form excludes.

California's eCPR system requires each worker's full Social Security number (or an FEIN for a sole proprietor) and home address in every electronic certified payroll on a state public works project; the Department of Industrial Relations redacts them before public release. New York's portal asks for home addresses and the last 4 digits of the SSN. Washington's L&I system and Illinois' Certified Transcript of Payroll require home addresses.

None of that changes the federal rule. A contractor on a project with both federal and state prevailing wage coverage files a WH-347 without SSNs and addresses to the federal chain, and a state report with them to the state portal. State requirements by state.

Practical handling

Store SSNs and addresses in your payroll system, where they already live, with access limited to the people who run payroll. Export certified payrolls with the employee number or last 4. If a prime or agency asks for full details, send them through a secure channel, once, and keep a note of who asked and when.

The people most exposed by a leaked payroll are your workers. The regulation's privacy rule is one of the few compliance obligations that costs nothing and protects them directly.