Totalization Agreement

A totalization agreement is a bilateral treaty that coordinates the Social Security systems of two countries. It stops a worker from paying Social Security taxes to both countries on the same earnings and helps people with mixed careers qualify for benefits.

The United States has signed these agreements with 31 countries, most recently Romania, which took effect on September 1, 2026, according to the Social Security Administration. HR teams meet the term when they send employees abroad.

How Does a Totalization Agreement Work?

Under the territoriality rule, a worker normally pays into the system of the country where the work happens. An employee on assignment can therefore owe contributions in two places.

An agreement assigns coverage to just one country and exempts the employer and employee from the other country's contributions, as the SSA's certificate of coverage guidance explains. A certificate of coverage proves the exemption.

Income tax stays separate, so rules such as federal income tax withholding still apply.

What Is the Detached-Worker Rule?

The detached-worker rule is the exception most HR teams rely on. A person temporarily transferred by the same employer stays covered only by the country that sent them.

In U.S. agreements, the rule generally applies when the assignment is expected to last five years or less. A U.S. employee sent abroad keeps paying into the U.S. program, and the employer pays only there as well.

When the employee works for a foreign affiliate, the American employer must hold a section 3121(l) agreement with the U.S. Treasury for U.S. coverage to continue. Italy's agreement is the exception and does not include this rule.

Which Scenarios Does a Totalization Agreement Cover?

Coverage depends on where the worker is employed and how long the assignment runs.

What Is a Certificate of Coverage and Who Requests It?

A certificate of coverage is the proof of exemption. When an agreement assigns coverage to the United States, the SSA issues a certificate showing that the employee and employer owe no Social Security tax abroad.

Employers generally request certificates for employees they transfer abroad, and the SSA now accepts requests through its online certificate service. Request it before the assignment starts.

In the other direction, the IRS explains that a worker needs a certificate from the home country's social security agency and gives it to the U.S. employer. Keep it on file, because the IRS may ask why no tax was withheld.

How Is a Totalization Agreement Different From a Tax Treaty?

A tax treaty addresses income tax. A totalization agreement addresses Social Security contributions and benefit eligibility. An expatriate can fall under both.

Our guide to resident and nonresident alien tax rules shows how status changes income tax withholding.

How Should HR Manage Totalization Agreements?

Treat each international assignment as a compliance checkpoint. These steps keep contributions and documents in order:

• Confirm the destination appears on the SSA's current agreement list before approving the assignment.
• Track expected assignment length against the five-year limit.
• Request the certificate before departure and store foreign certificates in the personnel file.
• Coordinate with global payroll compliance so payroll stops or continues the right contributions.
• Review your Social Security tax withholding setup after any assignment change.

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Frequently Asked Questions

Q: How many countries have a totalization agreement with the United States?

A: The SSA lists 31 countries, from Italy in 1978 through Romania in 2026. Confirm the list before each assignment.

Q: Is an employer required to request the certificate of coverage?

A: Employers generally request certificates on behalf of employees they transfer abroad. Self-employed people request their own.

Q: What happens if an assignment runs longer than five years?

A: Coverage generally shifts to the host country. Contact the SSA early if you expect an extension.

Q: Can a self-employed person use a totalization agreement?

A: Yes. A self-employed U.S. citizen or resident attaches a copy of the foreign certificate to the tax return each year.

Q: How do I contact the SSA about a certificate of coverage?

A: Email certificate@ssa.gov or call 1-866-776-4383, Monday through Friday, 8 a.m. to 3 p.m. Eastern time.

Q: What if the destination country has no agreement with the United States?

A: The worker and employer may owe contributions in both countries, so budget for the dual cost.