Tax treaties and totalization agreements: what they really do for Americans abroad

A tax treaty almost never lowers your US income tax as a citizen. A totalization agreement can spare you a second set of Social Security contributions every year. Most Americans abroad assume it's the other way around, and plenty find out the hard way around April 15.

The short version

• US income tax treaties mainly protect residents of the other country. They do "not reduce the US taxes of US citizens," with certain exceptions. That's the saving clause [1].
• Your main protection against double income tax is the US foreign tax credit and the foreign earned income exclusion, not the treaty itself [1][2][6].
• Treaties still matter for tie-breaker residency, certain pensions and benefits, and how income is sourced. A treaty-based position may need Form 8833 [1].
• Totalization agreements are separate Social Security agreements. They stop you paying into two systems on the same pay, and they let you combine work credits. The US has 31, including Romania from September 1, 2026 [3].
• Self-employed Americans abroad usually owe US self-employment tax unless a totalization agreement assigns them to the other country, which is proven with a certificate of coverage [3].

What a US tax treaty does

Uncle Sam has income tax treaties with a number of countries. Under them, residents of the other country can qualify for reduced US tax rates or exemptions on certain US-source income, such as dividends, interest and royalties. The rates vary by country and type of income [1]. Treaties also set rules for:

• Who is a resident when two countries both claim you. Tie-breaker tests usually look at your permanent home, then your center of vital interests, then your habitual abode and finally your nationality.
• Which country taxes first, for example on employment income, business profits, pensions and government pay.
• Relief from double taxation, usually by requiring each country to give a credit for the other's tax.
• Exchange of information between tax authorities and a mutual agreement procedure for disputes.

The saving clause: why citizens get the short end of the stick

Here's the part that surprises people. Almost every US treaty includes a saving clause. It lets the US tax its citizens (and green card holders treated as residents) as if the treaty didn't exist. The IRS says: "With certain exceptions, they do not reduce the US taxes of US citizens or US treaty residents," who are taxed on worldwide income [1].

In practice, if the treaty with your host country says a salary is taxable only where you live, that binds your host country's treatment of a US resident. It doesn't stop the IRS from taxing you as a citizen. You fall back on the foreign tax credit (Form 1116) or the exclusion (Form 2555) to avoid paying twice.

The exceptions to the saving clause

Each treaty lists articles that still apply to citizens. They differ from treaty to treaty, so read the saving clause paragraph (usually in Article 1) of your host country's treaty. Common categories include:

• Relief from double taxation, the article requiring the US to give a foreign tax credit. Some treaties use it to re-source income so the credit works. Income re-sourced by a treaty goes in its own category on Form 1116 [5].
• Social Security and some pension provisions in certain treaties.
• Non-discrimination and the mutual agreement procedure.
• Sometimes alimony, child support or government service pay.

If you take a position on your return that relies on a treaty to override US tax law, you generally must disclose it on Form 8833, Treaty-Based Return Position Disclosure [1]. Dual residents who claim to be residents of the other country under a tie-breaker file as nonresidents and attach Form 8833 [1]. For citizens, this is rare but possible, for example when a treaty exception applies to a pension.

Treaties change, so read the current text and Treasury's technical explanation for your country. It's dry reading, but it's the real deal. A US expat tax preparer can check whether an exception applies to you.

What treaties don't do

• They don't get you out of filing a US return, an FBAR or Form 8938.
• They don't cover US state income tax in most cases. Some states don't follow federal treaties at all.
• Income tax treaties don't cover Social Security contributions. That's what totalization agreements are for.

Totalization agreements: Social Security without paying twice

Without an agreement, an American working abroad can get hit twice, owing both US Social Security and Medicare tax (FICA, or self-employment tax) and the host country's social insurance on the same earnings. Totalization agreements fix two problems: they eliminate dual Social Security taxation, and they fill gaps in benefit protection for people whose careers are split between countries [3].

The countries with an agreement

According to the Social Security Administration, the US has agreements with these 31 countries [3]:

Heads-up: Mexico, the UAE, Thailand, Singapore, the Philippines and most of Latin America and Asia aren't on the list. If you live in one of those countries, there's no Social Security agreement with the US.

Which country covers you

The general rule is that you pay into the system of the country where you work. The main exception is for detached workers. If a US employer temporarily sends you abroad on an assignment expected to last 5 years or less, you stay in US Social Security only and are exempt in the host country. The Italy agreement is a special case and has no detached-worker rule [3].

For employees, there's one more wrinkle. If you're hired locally by a foreign employer, you usually pay only into the local system. That may already be the case without an agreement, because FICA generally doesn't apply to a foreign employer. Agreements matter most when a US employer or a US-controlled affiliate is involved.

Self-employed Americans

This is where agreements really earn their keep. The SSA says self-employed US citizens working abroad are usually covered by both countries without an agreement [3]. US self-employment tax (Schedule SE) isn't reduced by the foreign earned income exclusion, so a freelancer in a non-agreement country often pays the full US self-employment tax plus local contributions. That's a tough pill to swallow.

Many US agreements resolve this by assigning self-employment coverage to the country of residence. If you live in Germany or Australia and work for yourself, you'd generally pay there and be exempt from US self-employment tax [3]. Each agreement has its own rules, so check the SSA description for your country.

Getting a certificate of coverage

The exemption isn't automatic, and the paperwork is on you. You prove it with a certificate of coverage from the country that keeps covering you [3]:

1. Figure out which country covers you under the agreement, using the SSA agreement description for your host country.
2. If you stay in the US system (a detached worker, or a self-employed person assigned to the US), request a US certificate. Employers and self-employed people can apply online through SSA's certificate of coverage forms, or by mail to SSA's International Support Unit in Baltimore [4].
3. If you're covered by the host country, request its certificate from its social security agency.
4. Give the certificate to the right party. Employees give it to their employer or the foreign agency. Self-employed people covered abroad attach a copy of the foreign certificate to their US tax return each year as proof of their exemption from US self-employment tax [3].
5. Keep it current. Certificates cover a set period, so renew when an assignment is extended.

Benefits: totalizing credits

The second half of an agreement helps you qualify for benefits. If you don't have the 40 US credits normally needed for a retirement benefit, an agreement can let SSA count your periods of coverage in the other country toward eligibility. The benefit is then prorated to reflect only your US coverage [3]. The other country does the same in reverse. If your spouse or partner is Australian, our sister site ExpatCooee explains what happens to their super while you live overseas.

Sources

1. IRS: Tax treaties
2. IRS: US citizens and resident aliens abroad
3. SSA: US international Social Security agreements, overview
4. SSA: Certificates of coverage
5. IRS: Instructions for Form 1116 (2025)
6. IRS: Publication 54 (12/2025), Tax Guide for US Citizens and Resident Aliens Abroad

Keep reading

• Foreign earned income exclusion vs foreign tax credit
• Self-employed abroad: US self-employment tax
• Social Security abroad: payments and restrictions
• Filing a US tax return from abroad