Social Security tax for expats and self-employed Americans

For the 2025 tax year filed in 2026, US Social Security tax can still apply when an American works abroad, but the result depends on employee status, employer location, self-employment, and any Totalization Agreement. The 2025 Social Security wage base is $176,100, with a 6.2% employee rate.

This guide separates payroll tax from benefit taxation, shows when coverage shifts to a foreign system, and explains the records that support an exemption. It also reflects the Social Security Fairness Act, which ended WEP and GPO reductions for benefits payable from January 2024 forward.

Do expats pay into Social Security?

Expats may pay into US Social Security while abroad when US employment-tax rules cover their wages or self-employment income. For 2025, covered employee wages face a 6.2% Social Security rate up to $176,100, while a Totalization Agreement can assign the work to only one country’s system.

Do expats pay Social Security tax? The answer depends on these 3 common work arrangements:

• US employee abroad: A worker sent abroad by an American employer may remain under US Social Security, especially during a qualifying temporary assignment. See how working abroad for a US company affects payroll and filing.
• Foreign employee abroad: A worker hired by a foreign employer for services performed outside the United States is not automatically subject to US FICA. Coverage can change if an agreement or special US rule applies.
• Self-employed expat: A US citizen or resident generally remains subject to US self-employment tax on net earnings of $400 or more unless a Totalization Agreement assigns coverage abroad. TFX’s guide to self-employment tax on foreign income explains the Schedule SE rules.

A US employee transferred to Germany for 3 years can remain in US coverage under the US–Germany agreement if the detached-worker conditions are met, rather than paying mandatory contributions to both systems on the same earnings.

What is Social Security tax?

Social Security tax is the Old-Age, Survivors, and Disability Insurance portion of US employment tax, usually paid through FICA by employees and employers or SECA by self-employed workers. For 2025, the Social Security portion is 12.4% in total and stops at $176,100 of covered earnings.

It is one part of the US payroll-tax system, separate from the 2.9% combined Medicare tax. The IRS rules for Social Security tax consequences of working abroad explain when services outside the United States remain covered.

For 2025, Social Security stops at $176,100 of covered earnings, while Medicare has no wage-base cap.

 

The following 3 worker groups should identify their coverage rule before assuming where contributions belong:

• Employees should check who employs them and where the services are performed.
• Self-employed workers should use the Schedule SE guide to review net earnings and any agreement-specific self-employment rule.
• Expats in agreement countries should secure a certificate of coverage when one is required to document the single-system result.

For a broader filing context, TFX’s US expat tax guide explains how employment taxes fit alongside Form 1040, Form 2555, Form 1116, FBAR, and other expat filings.

Definition and purpose

The federal Social Security tax funds retirement, disability, and survivor benefits under Title II of the Social Security Act. For 2025, one Social Security credit requires $1,810 of covered earnings, and workers can earn up to 4 credits for the year, although eligibility rules vary by benefit.

The following 3 categories summarize what your contributions support:

• Retirement benefits: Monthly benefits for eligible workers who have enough covered work credits.
• Disability benefits: Payments for insured workers who meet Social Security’s disability and work-history requirements.
• Survivor benefits: Payments that may be available to eligible family members after a covered worker dies.

Do I have to pay Social Security tax? The answer depends on whether your work is covered by FICA or SECA and whether an international agreement shifts coverage. The IRS’s Social Security income FAQs address benefit-income questions, while TFX explains Social Security benefits for Americans living abroad.

Paying into covered employment can matter because work credits establish insured status, while your earnings record helps determine the benefit amount. TFX also explains ways Social Security benefits may be reduced while living overseas, including rules separate from payroll-tax coverage.

FICA vs. SECA

FICA and SECA collect Social Security and Medicare taxes through 2 different systems: FICA splits payroll taxes between employee and employer, while SECA places the combined responsibility on a self-employed person. For 2025, the Social Security component is 12.4% in either system before agreement-based coverage rules are applied.

The main distinction is who remits the tax: FICA divides the 12.4% Social Security component, while SECA starts with the self-employed worker.

 

The IRS rules for US citizens and residents employed abroad by American employers explain when FICA follows wages outside the United States. If you are self-employed abroad, SECA is the rule to watch, subject to a Totalization Agreement that assigns coverage to another country.

Current rates and wage base limits

For 2025, the Social Security tax rate is 6.2% for the employee and 6.2% for the employer, or 12.4% combined, on wages up to $176,100. The Medicare rate is 1.45% each with no wage cap, while self-employment tax is generally 15.3% before adjustments.

The 2025 Social Security wage base limit is $176,100, so the maximum employee Social Security withholding is $10,918.20.

 

Based on our client scenario at TFX: an employee with $80,000 of covered 2025 wages has $4,960 of employee Social Security tax. An employee with $200,000 of covered wages reaches the $176,100 cap, so employee Social Security withholding stops at $10,918.20, although Medicare continues.

How does the Social Security tax work once wages cross the 2025 base? The 6.2% Social Security withholding stops after covered wages reach $176,100, while Medicare withholding continues because Medicare has no wage-base cap.

The wage base changes annually. TFX’s update on the 2025 Social Security taxable wage base explains the move to $176,100, while 2025 Publication 15 confirms the employee and employer payroll rates for this return year.

For later payroll years, use the IRS current Publication 15 employer tax rules. The IRS also lists the Additional Medicare Tax thresholds, which are based on filing status even though an employer starts withholding the extra 0.9% after paying an employee more than $200,000 of Medicare wages.

 

 

Need help identifying which payroll rule applies to your 2025 foreign work arrangement? Ask about your payroll tax.

Totalization Agreements

A Totalization Agreement coordinates US and foreign social-insurance rules so the same work is generally covered by only 1 country’s system and qualifying credits can be combined for benefit eligibility. As of August 10, 2026, the United States has agreements with 30 countries, according to the Social Security Administration.

The following 3 benefits are the main reasons an agreement matters:

• It can prevent mandatory Social Security contributions to 2 systems on the same covered earnings.
• It clarifies earning Social Security credits while working abroad: US-covered work earns US credits, while eligible foreign coverage can be totalized for entitlement without becoming US credits.
• It determines which country’s coverage law applies to a particular employee or self-employed worker.

TFX explains the coverage mechanics in its guide to what Totalization Agreements mean for US expat taxes.

For assignment and liability context, review TFX’s bilateral Social Security agreements guide. The SSA’s official overview of US international Social Security agreements is the source to confirm whether a country is currently covered.

Simple yes/no coverage flow: Is your work country on SSA’s current agreement list?

No → apply US and foreign domestic rules separately and check for possible dual contributions.

Yes → identify whether you are locally hired, temporarily transferred, or self-employed, then obtain the certificate required by the applicable agreement.

For US coverage, SSA states that Totalization Agreements coordinate both Social Security and Medicare payroll taxes. They do not provide Medicare healthcare coverage abroad or create entitlement to Supplemental Security Income.

Purpose and benefits

Totalization Agreements address 3 recurring cross-border problems: duplicate payroll contributions, temporary-assignment coverage, and gaps in benefit eligibility when a career spans 2 systems. The agreements do not erase either country’s domestic law; they assign coverage under treaty rules and can allow qualifying credits to be combined for entitlement purposes.

The following 3 benefits explain the practical value:

• Prevent dual payroll taxes: Covered earnings are generally assigned to one system rather than both.
• Clarify temporary assignments: A qualifying detached worker can usually remain in the home system for 5 years or fewer under most agreements.
• Preserve benefit continuity: Credits from an agreement country may help satisfy minimum eligibility when US credits alone are insufficient.

Based on our client scenario at TFX: a US employee sent to France for a 4-year assignment remains under US coverage when the detached-worker rule applies and uses a certificate of coverage to document exemption from French contributions on the same work. TFX’s certificate of coverage and A1 guide explain the proof needed.

Countries with US Totalization Agreements

As of August 10, 2026, the United States has 30 Social Security agreements in force, and each includes rules for employees and self-employed workers, although the assignment tests are country-specific. SSA should be checked before relying on any older list because a new agreement or amended rule can change coverage.

All 30 current agreement countries coordinate employee and self-employed coverage, but the exact rule for self-employment and temporary transfers must be checked country by country.

 

TFX’s Social Security expat Q&A gives additional background, but current coverage should be confirmed against SSA because older articles can predate later agreements or legislative changes.

The US–UK Totalization Agreement

The US–UK Totalization Agreement generally assigns a worker to 1 Social Security system and includes rules for temporary transfers and self-employment. A US employee sent to the United Kingdom for 5 years or fewer can remain under US coverage when the detached-worker conditions are met.

For a temporary US-to-UK transfer of 5 years or fewer, US coverage can continue; local hires and UK-resident self-employed workers usually fall under UK coverage.

 

SSA’s US–UK Totalization Agreement guidance sets out the employee, self-employment, certificate, and benefit rules. TFX’s US–UK tax treaty guide covers income-tax treaty rules, which are separate from Social Security totalization.

Based on our client scenario at TFX: Maya works for the same US employer before and during a 36-month London assignment. If the agreement assigns her to US coverage, her employer keeps the US certificate showing why UK compulsory contributions do not apply to the covered work.

Dual nationals can also review TFX’s US–UK dual-citizenship tax guide for the broader filing context.

Certificate of coverage

A certificate of coverage is the document that proves which country’s Social Security system applies under an agreement and supports exemption from compulsory contributions in the other country. For a 2025 assignment with US-assigned coverage, SSA issues the certificate; for foreign-assigned coverage, the relevant foreign social-insurance authority normally issues it.

The following 3 steps should be built into an overseas assignment:

1. Before departure: Request the certificate as early as possible, ideally before work begins, using the SSA certificate of coverage process when US coverage applies.
2. During the assignment: Give the certificate to the employer or foreign authority if requested and keep a copy with payroll records.
3. If questioned or audited: Produce the certificate and the assignment facts supporting the agreement rule; self-employed workers should follow the country-specific instruction for attaching proof to the US return.

 

 

Missing documentation does not necessarily change which agreement rule applies, but it makes a dual-contribution dispute harder to resolve. Keep the certificate, employment agreement, assignment dates, and payroll statements together.

Detached-worker rule: 5-year exemption for temporary assignments

Under most US Totalization Agreements, an employee sent from one agreement country to another for 5 years or fewer can remain under the sending country’s Social Security system. Italy is excluded from SSA’s standard employee table; for Denmark, the 3-year exception applies only to Denmark-to-US transfers.

The following 3 conditions commonly support detached-worker treatment:

• The worker was sent from one agreement country to the other rather than hired locally there.
• The assignment is expected to fit within the agreement’s temporary period, commonly 5 years or fewer.
• The employment relationship and agreement-specific employer conditions continue during the assignment.

Based on our client scenario at TFX: an employee leaves the United States on July 1, 2025 for a 4-year assignment ending June 30, 2029. If the applicable agreement’s detached-worker conditions are met, US coverage can continue for that assignment, backed by a certificate.

The following 2 distinctions keep employee and self-employment rules separate:

• Employee assignment: The detached-worker rule usually focuses on who sent the worker, the expected assignment period, and the continuing employment relationship.
• Self-employment: Agreement rules vary more by country; some use residence, while others allow a temporary transfer of self-employment activity.

Implications for US expats

For 2025, the expat Social Security tax result turns on work status, employer type, location, and any Totalization Agreement, not citizenship alone. A US citizen abroad can owe US Social Security through FICA or SECA, owe only foreign social insurance, or qualify for single-system coverage under an agreement.

The decision rule is work-specific: identify employee versus self-employed status first, then test employer location and any agreement before calculating 2025 contributions.

 

The following 3 takeaways connect the rules to filing:

• Social Security coverage while living abroad is not determined solely by where your home is; covered employment and agreement rules control.
• US expat Social Security questions should separate contributions, benefit eligibility, and income-tax treatment because each has a different rule set.
• Tax on Social Security income is calculated under benefit-tax rules, not the FICA or SECA rules that apply while you are working.

So, how is Social Security taxed for an expat? Payroll contributions are imposed on covered work, while up to 85% of benefits can later be included in taxable income when the 2025 combined-income thresholds are crossed. The taxation of Social Security benefits is addressed separately below because foreign pensions and investment income can affect the calculation.

Need help matching your foreign work to the right 2025 filing forms and coverage records?

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Working abroad

A US citizen working overseas does not owe FICA merely because of citizenship, but US coverage can continue when an American employer pays for services abroad, or an agreement assigns US coverage. For 2025, employee Social Security wages are taxed at 6.2% up to $176,100.

The following 3 work arrangements produce different results:

• US employer: Review whether the employer meets the US definition and whether a Totalization Agreement changes the default result.
• Foreign employer: Wages for services outside the United States are not automatically pulled into US FICA solely because the employee is American.
• Temporary assignment: A qualifying detached-worker rule can keep a transferred employee in the home-country system for a defined period.

The Social Security tax abroad describes the same coverage question: which system taxes the work? Social Security tax on foreign earned income also depends on the employment relationship, because the Foreign Earned Income Exclusion does not itself switch off FICA or SECA.

A worker concerned about Social Security tax living abroad should first identify the employer and agreement rule, then obtain a certificate if the foreign system or US system grants an exemption from the other country’s contributions.

Self-employed abroad

US citizens and resident aliens who are self-employed abroad owe US self-employment tax when net earnings from self-employment reach $400, unless a Totalization Agreement assigns that work to a foreign system. For 2025, Schedule SE applies the Social Security component subject to the $176,100 combined wage base.

The IRS’s self-employment tax guidance for businesses abroad confirms that US citizens and resident aliens abroad are generally subject to US self-employment tax unless an applicable agreement provides an exception.

2026 filing-season update: If a Totalization Agreement exempts 2025 self-employment income from US SE tax, follow the IRS’s February 20, 2026 correction to the 2025 Schedule SE instructions. Attach the required coverage statement or certificate to Form 1040, Form 1040-SR, or Form 1040-NR; on Schedule 2, line 4, check box 3 and enter “EAS.”

A self-employed expat should not claim an agreement exemption without the coverage proof required for the country involved.

 

Based on our client scenario at TFX: a US freelance designer has $100,000 of 2025 Schedule C net profit and no agreement exemption. The regular SE calculation starts with 92.35% of net profit, or $92,350, producing about $14,129.55 of combined 15.3% Social Security and Medicare self-employment tax before any Additional Medicare Tax.

Does a foreign certificate remove US SECA from your earnings? Find out.

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Claiming benefits

US citizens who qualify for Social Security can usually receive retirement, disability, or survivor benefits abroad, subject to country-specific payment restrictions. Most workers need 40 US credits for retirement benefits, but a Totalization Agreement can count qualifying foreign credits when US credits alone are insufficient.

The following 3 steps help an expat prepare a claim:

• Confirm US insured status and work credits through SSA records.
• If US credits are short, check whether an agreement lets SSA count qualifying foreign coverage periods for eligibility; SSA requires at least 6 US credits before foreign credits can be totalized for a US benefit.
• Use SSA’s payments outside the United States guidance to check whether benefits can continue in the country where you live.

So, can expatriates collect Social Security? US citizens can generally receive eligible benefits abroad, although payment restrictions can apply in certain countries. TFX also explains what can happen to Social Security benefits after renouncing US citizenship. A non-US citizen receiving benefits can face different withholding rules, covered separately in TFX’s nonresident alien Social Security tax guide.

 

Are Social Security benefits taxable for US expats?

Yes. US Social Security benefits can be federally taxable for a citizen abroad, with up to 85% included in taxable income depending on combined income and filing status. For 2025, the first base threshold is $25,000 for single filers and $32,000 for married couples filing jointly.

The IRS explains when Social Security benefits may be taxable, and its Social Security benefits taxability tool can help with standard cases. The detailed 2025 calculation is in Publication 915, with treaty rules checked separately when relevant.

For 2025, the main combined-income thresholds are $25,000/$34,000 for single-type filers and $32,000/$44,000 for married filing jointly.

 

Benefit-tax calculations use combined income, which generally starts with adjusted gross income, adds tax-exempt interest, and adds one-half of Social Security benefits, with statutory adjustments. Foreign pension or investment income included in US income can push the total over a threshold even when the Social Security payment itself has not changed.

Based on our client scenario at TFX: a single retiree abroad has $20,000 of other US-taxable income and $20,000 of Social Security benefits. Adding one-half of the benefits gives $30,000 before other required adjustments, which is above the $25,000 base amount and can make part of the benefits taxable.

2026 filing-season update: For tax years 2025–2028, eligible taxpayers age 65 or older can claim an enhanced deduction of up to $6,000 per person, or up to $12,000 on a joint return if both spouses qualify. The deduction begins to phase out above $75,000 of modified adjusted gross income for single, head-of-household, and qualifying-surviving-spouse filers, or $150,000 for married filing jointly. Eligible individuals need a valid SSN, and married taxpayers must file jointly to claim the deduction. It can reduce federal taxable income, but it does not change the Social Security combined-income thresholds or the rule that up to 85% of benefits can be included in income.

TFX’s taxes in retirement guide covers pensions, IRAs, and other retirement income that can interact with this calculation.

Retirees coordinating benefit income with retirement-account withdrawals can also review IRAs and Roth IRAs for Americans living abroad. The exact US result can change under a tax treaty that specifically addresses Social Security benefits.

Foreign Social Security taxes and the US Foreign Tax Credit

A foreign social-insurance contribution is not automatically creditable in the United States. For 2025, FTC applies to qualifying income taxes or taxes in lieu of income tax. IRS Publication 514 bars a deduction or credit for Social Security taxes paid to a country covered by a Social Security agreement.

This distinction matters when comparing Social Security and taxes across 2 countries. TFX’s Foreign Tax Credit guide explains when Form 1116 is used for qualifying foreign income taxes.

After a payment is classified as a creditable income tax, TFX’s Foreign Tax Credit vs. deduction comparison explains the separate income-tax choices.

Foreign payroll contributions and foreign income taxes are different: only a tax that satisfies the US Foreign Tax Credit rules can enter the Form 1116 calculation.

 

The IRS’s foreign taxes that qualify for the Foreign Tax Credit guidance and 2025 Publication 514 distinguish qualifying foreign income taxes from foreign Social Security contributions covered by an agreement.

A foreign social-insurance charge may therefore need to be handled through a Totalization Agreement rather than Form 1116. This is why a worker can face different answers for foreign payroll tax and foreign income tax even when both are withheld from the same paycheck.

Practical steps and compliance

For a 2025 return filed in 2026, Social Security compliance starts with 4 records: employment status, employer identity, agreement coverage, and proof of contributions or exemption. The filing result can involve Form W-2, Schedule SE, Form 1040, a certificate of coverage, or foreign social-insurance documents depending on the facts.

The following 4-step workflow keeps the coverage question separate from the income-tax return:

1. Classify the worker as an employee or self-employed person for the activity involved.
2. Identify whether US FICA or SECA applies under domestic rules.
3. Check the current SSA agreement list and obtain a certificate when coverage is assigned to one country.
4. Reconcile US payroll records, foreign contributions, and the 2025 Form 1040 filing position.

Before filing, the following 4 records should be available where relevant:

• US and foreign wage statements or payroll reports.
• Schedule C records and net self-employment earnings.
• Certificate of coverage and assignment dates.
• Foreign income-tax and social-insurance payment records kept separately.

The IRS’s current guidance for US citizens and resident aliens abroad provides the broader federal-return context.

Before gathering the final return package, use TFX’s expat IRS form checklist to identify the forms tied to income, accounts, and ownership.

TFX’s tax document checklist can then help organize wage statements, certificates, foreign tax records, and other support before preparation.

Filing requirements

Self-employed US citizens and residents generally file Schedule SE when 2025 net earnings from self-employment meet the $400 threshold, unless an agreement provides an exemption for the covered activity. Employees rely on payroll reporting, while expats may also need Form 1040 and international forms unrelated to Social Security tax.

The form depends on the work arrangement, and the 2025 return filing calendar runs through June 15 and October 15, 2026 for qualifying expats and timely extensions.

 

For 2025 calendar-year returns, qualifying taxpayers abroad received an automatic filing extension to June 15, 2026, while Form 4868 can extend filing to October 15, 2026 when timely requested. Interest on unpaid federal income tax generally runs from April 15, 2026, even when the expat filing extension applies.

TFX’s 2026 guide to US tax forms for expats covers related forms.

If more filing time is needed, our tax extension guide explains the June 15 and October 15 dates for qualifying taxpayers abroad.

Avoiding double taxation

Avoiding duplicate Social Security contributions requires applying the coverage agreement before relying on an income-tax credit. For 2025, a 5-year-or-shorter temporary assignment may remain in the home system under many agreements, while local employment and self-employment can follow different country-specific rules that must be documented.

The following 4 steps are the most useful order of operations:

1. Identify assignment length and exact work dates.
2. Confirm the employer’s legal status and whether the worker was transferred or hired locally.
3. Apply the country’s Totalization Agreement, if one exists, including its self-employment rule.
4. Obtain the certificate and correct payroll withholding before both systems collect contributions.

Based on our client scenario at TFX: a US worker moves to a non-agreement country for 18 months, and both domestic systems impose payroll contributions. A Foreign Tax Credit cannot automatically cure the duplicate Social Security cost because foreign social-insurance payments must first satisfy the separate FTC rules.

TFX’s current guide to double taxation and ways to avoid it explains how income-tax credits and treaties differ from payroll-tax coordination.

Seeking professional advice

Professional review is most useful when 2 countries can assert payroll coverage, a certificate was never obtained, or self-employment and employee wages overlap in the same year. For a 2025 return, those facts can affect Schedule SE, payroll corrections, Form 1116, and benefit-credit records in different ways.

The following 4 adviser checks are more useful than a generic “international tax” label:

• Experience with expat payroll and US FICA outside the United States.
• Familiarity with country-specific Totalization Agreements and certificates of coverage.
• Ability to separate self-employment tax from income-tax tools such as FEIE and FTC.
• Familiarity with Social Security benefit-tax rules and foreign pensions.

Before engaging someone, the following 3 questions can reveal whether the issue is within their scope:

• Which agreement article or domestic rule assigns my 2025 work to one system?
• What certificate or payroll record supports the exemption?
• Which part belongs on Schedule SE, Form 1116, or neither?

TFX’s guide on when to hire an expat tax professional explains what to compare. For situations where US tax remains after expat tax relief, review the common reasons US expats may still owe the IRS.

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Conclusion

For 2025, US expats owe Social Security tax when wages or self-employment income fall within US coverage rules after any applicable Totalization Agreement is applied. The key numbers are a 6.2% employee rate, a $176,100 wage base, and a $400 Schedule SE threshold for covered self-employment.

The following 4 points are worth carrying into a 2025 return filed in 2026:

• Check employee versus self-employed status before calculating contributions.
• Confirm whether the work country is one of the 30 agreement countries.
• Obtain and retain a certificate of coverage when an agreement assigns single-system coverage.
• Separate payroll contributions from the income-tax rules that determine whether benefits are taxable.

If cross-border payroll, self-employment, or benefit income affects your return, compare the agreement rule and filing records before submitting Form 1040. This article is educational and does not replace advice based on your employment contract, country, treaty, and full tax facts.