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Topic · US expat tax

US Social Security & Self-Employment Tax Abroad (WEP, Totalization)

How totalization agreements prevent double social tax, what a certificate of coverage does, how the Windfall Elimination Provision can reduce benefits, and the self-employment tax rate.

By Danilson Ramos · Founder, Atamatax

Published June 2026 · Updated September 2026

U.S. Social Security abroad has two sides: what you pay in while working overseas, and what you get out in benefits later. Both can surprise expats — especially the self-employed, who face the full self-employment (SE) tax, currently around 15.3% on net self-employment earnings, which the FEIE does not reduce.

Totalization agreements: avoiding double social tax

A totalization agreement is a U.S. social-security agreement with another country, designed to stop you paying into two social-security systems on the same earnings and to coordinate benefit eligibility. The U.S. has these with a number of countries. Where one exists, it generally assigns your coverage to one country for a given period. (This is the same mechanism covered on the totalization-agreements topic.)

Totalization agreements cover social-security / SE tax, not income tax. A country can have an income-tax treaty but no totalization agreement — so it's worth checking specifically whether a totalization agreement exists for your country.

Self-employed: who covers you, and the certificate

For the self-employed, the agreement generally points coverage to one system, proven to the IRS with a certificate of coverage:

SituationOften covered byEffect on U.S. SE tax
Self-employed in an agreement countryCountry of residenceMay be exempt from U.S. SE tax with a certificate of coverage
Temporarily 'detached' / posted abroadHome country, for a limited periodStays in the home system during the posting
Working where there's no agreementPotentially both systemsU.S. SE tax (~15.3%) can apply with no offset for local social tax
Where an agreement assigns you to the other country's system, you generally obtain a certificate of coverage from that country's social-security authority and keep it to support excluding the earnings from U.S. SE tax.

Benefits and the Windfall Elimination Provision (WEP)

On the benefit side, the Windfall Elimination Provision (WEP) can reduce U.S. Social Security benefits for people who also receive a pension from work not covered by U.S. Social Security — which can include certain foreign pensions. WEP doesn't eliminate benefits, but it can lower them, and the rules have been subject to legislative attention over time, so the current-year position is worth confirming.

  • The FEIE does not reduce SE tax; relief usually comes from a totalization agreement.
  • A certificate of coverage is the practical proof of which system covers you.
  • WEP can reduce U.S. benefits where a non-covered (e.g. foreign) pension is also received — an evolving area.

Self-employed abroad or worried about WEP on your benefits?

The free Tax Risk Check helps you think through totalization, SE-tax exposure, and benefit questions. Atamatax provides preparation support; this is not individualized tax or legal advice.

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Authorities cited

  • IRC §1401 — IRC §1401 — Rate of self-employment tax
  • IRC §911 — IRC §911 — Foreign earned income exclusion + housing exclusion/deduction

Primary sources (Cornell Legal Information Institute for the US Code and CFR; IRS.gov for forms, procedures, and treaty documents). This page is general information, not individualized tax or legal advice.

Atamatax provides tax preparation support and educational resources. This website does not constitute legal or tax advice.

Frequently asked questions

Does the FEIE remove my US self-employment tax?#
No — the Foreign Earned Income Exclusion reduces U.S. income tax on earned income but not self-employment (Social Security/Medicare) tax, which is currently around 15.3%. Relief from U.S. SE tax usually comes from a totalization agreement, not the FEIE.
What is a certificate of coverage?#
It's a document from a country's social-security authority showing which system covers you under a totalization agreement. Where the agreement assigns you to the other country, you generally keep the certificate to support excluding those earnings from U.S. SE tax.
Will the WEP reduce my US Social Security benefits?#
It can — the Windfall Elimination Provision may reduce U.S. benefits for people who also receive a pension from work not covered by U.S. Social Security, which can include certain foreign pensions. The rules have seen legislative attention, so confirm the current-year position rather than assuming.
How is a foreign sole proprietorship reported by a US person?#
A local independent registration — auto-entrepreneur, Einzelunternehmen, ditta individuale, sole trader — is generally not a separate entity for US purposes, so the business income goes on Schedule C of your own return and the net earnings run through the self-employment tax computation described above. Two things routinely catch people out. First, the FEIE does not touch self-employment tax, so excluding the income does not remove the charge — only a totalization agreement assigning coverage to the other country does. Second, a foreign branch or business operation can bring Form 8858 into play, an information return with a penalty attached that has nothing to do with how much tax is due. Atamatax computes Schedule C and the self-employment tax; Form 8858 is routed to a professional for preparation.

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