A Deep Dive into Mexico and Spain

Moving abroad can be exciting. For many Americans, countries like Mexico and Spain offer a different pace of life, lower living costs in some areas, strong cultural appeal, and the opportunity to work remotely, retire abroad, or experience something new.

But moving abroad also creates one major financial complication that many people underestimate: taxes.

A common assumption is that once you leave the United States, you also leave the U.S. tax system behind. Unfortunately, that is not how it works for U.S. citizens and green card holders.

The United States generally taxes its citizens and permanent residents on their worldwide income regardless of where they live. That means income earned in Mexico, Spain, or almost anywhere else may still need to be reported to the IRS.

At the same time, the country where you live may also consider you a tax resident and may tax your worldwide income under its own rules.

In other words, moving abroad does not necessarily replace one tax system with another. In many cases, it adds a second tax system on top of the first.

The good news is that this does not automatically mean paying full tax twice on the same income. The U.S. tax code includes mechanisms such as the Foreign Earned Income Exclusion and Foreign Tax Credit, and the United States has tax treaties with both Mexico and Spain.

The challenge is that these protections are not automatic. You generally have to file the correct returns, claim the appropriate exclusions or credits, and understand how the rules interact.

That is where many expensive mistakes happen.

An American working remotely from Madrid may face a very different tax situation from an American retiree living in San Miguel de Allende. A self-employed consultant in Mexico may face issues that an employee in Spain does not. A retiree with a large Roth IRA may discover that another country does not treat that account the same way the IRS does. And someone who owns an Airbnb in Mexico may have tax obligations there even if the rental income is deposited into a U.S. bank account.

The details matter.

This guide looks at how the tax systems of the United States, Mexico, and Spain interact and focuses on the areas that tend to surprise Americans most.

We will cover:

• Why Americans abroad generally still file U.S. tax returns
• The Foreign Earned Income Exclusion
• The Foreign Tax Credit
• FBAR and FATCA reporting
• U.S. self-employment tax while living abroad
• State tax residency after leaving the United States
• Tax residency rules in Spain
• Tax residency rules in Mexico
• Income-tax rates in all three countries
• Spain’s Beckham Law
• Mexican rental-property and Airbnb taxation
• Roth IRAs, traditional IRAs, 401(k)s, and Social Security
• Inheritance, gifts, and wealth taxes
• FATCA, CRS, and cross-border information sharing
• What happens if you have not been filing correctly
• Planning opportunities to consider before moving

The goal is not to provide individualized tax advice. Cross-border taxation is extremely fact-specific, and the right answer can depend on your income, citizenship, residency status, visa, business structure, investments, retirement accounts, property ownership, and even which region of Spain you choose to live in.

The goal is to give you a practical framework for understanding the major rules before you move.

Americans Abroad Still Have U.S. Tax Obligations

The single most important tax concept for Americans living abroad is simple:

Moving outside the United States generally does not end your U.S. tax obligations.

The United States taxes its citizens on worldwide income. If you are a U.S. citizen or green card holder, the IRS generally still expects you to report income regardless of whether it was earned in Arizona, Mexico City, Madrid, or anywhere else in the world.

That can include:

• Salary and wages
• Self-employment income
• Business income
• Interest
• Dividends
• Capital gains
• Rental income
• Retirement distributions
• Other investment income

This differs from how many other countries approach taxation.

In many countries, tax liability is driven primarily by residency. If you become a resident, the country may tax your worldwide income. If you leave and are no longer a resident, that worldwide-income obligation may end.

For Americans, citizenship remains part of the equation.

That means an American living abroad can potentially be accountable to two tax authorities at once: the IRS and the tax authority of the country where they live.

In Mexico, that authority is the Servicio de Administración Tributaria, commonly called the SAT.

In Spain, it is the Agencia Estatal de Administración Tributaria, commonly called the Agencia Tributaria or Hacienda.

The real goal of cross-border tax planning is not simply to determine whether both countries can tax you. It is to determine which country has the primary taxing right, what credits or exclusions are available, what reporting is required, and how to avoid unnecessary double taxation.

The Foreign Earned Income Exclusion

One of the best-known tax provisions for Americans living abroad is the Foreign Earned Income Exclusion, commonly abbreviated as FEIE.

The FEIE allows qualifying taxpayers to exclude a certain amount of foreign earned income from U.S. federal income tax.

For 2026, the maximum exclusion is $132,900 per qualifying individual.

If both spouses qualify independently, each spouse may potentially claim the exclusion on their own earned income.

However, the FEIE applies only to earned income.

That generally includes:

• Wages
• Salary
• Certain self-employment income

It does not generally exclude:

• Dividends
• Interest
• Capital gains
• Rental income
• Pension income
• IRA distributions

That distinction is extremely important.

Someone earning a salary abroad may benefit significantly from the FEIE, while a retiree living primarily on investment income may receive little or no benefit.

To qualify, you generally need a foreign tax home and must meet either the Physical Presence Test or the Bona Fide Residence Test.

The Physical Presence Test generally requires you to be outside the United States for at least 330 full days during a qualifying 12-month period.

The Bona Fide Residence Test generally applies when you are a bona fide resident of a foreign country for an uninterrupted period that includes an entire tax year.

A Foreign Housing Exclusion or deduction may also help qualifying taxpayers offset certain housing expenses abroad.

However, one of the most important limitations of the FEIE is often missed:

It does not eliminate self-employment tax.

A self-employed American may qualify to exclude income from U.S. income tax and still owe U.S. Social Security and Medicare taxes on that same income.

The Foreign Tax Credit

The second major tool is the Foreign Tax Credit, or FTC.

The Foreign Tax Credit generally allows you to claim a U.S. tax credit for qualifying income taxes paid to a foreign country.

This is one of the main tools for reducing double taxation.

For example, if you are a tax resident of Spain and pay substantial Spanish income tax on your salary, you may be able to use those Spanish taxes as a credit against U.S. federal income tax imposed on the same income.

This is especially important in higher-tax countries.

Spain often falls into that category.

Because Spanish income-tax rates can exceed U.S. rates at many income levels, an American resident in Spain may pay most of their income tax to Spain and then use the Foreign Tax Credit to eliminate or significantly reduce their remaining U.S. income-tax liability.

Mexico can be different.

Depending on income level and circumstances, Mexican taxes may be lower than U.S. taxes. In those situations, the FEIE may sometimes be more useful.

There is no universal answer.

The FEIE and FTC interact with one another, and you generally cannot claim a Foreign Tax Credit for foreign tax attributable to income you excluded using the FEIE.

Choosing the correct approach can have long-term consequences, particularly because unused foreign tax credits may sometimes be carried to other tax years.

For Americans planning to live abroad for several years, this can become a meaningful planning decision, not just a filing decision.

FBAR: The Rule That Surprises Many Expats

Income tax is only part of the compliance picture.

Americans living abroad may also have separate foreign-account reporting requirements.

One of the most important is the FBAR, or Report of Foreign Bank and Financial Accounts.

You file the FBAR on FinCEN Form 114.

In general, if the aggregate value of your foreign financial accounts exceeds $10,000 at any point during the calendar year, you may have an FBAR filing obligation.

The word aggregate matters.

You do not need one individual account containing more than $10,000.

For example, if you had:

• $4,000 in a Mexican checking account
• $4,000 in a Spanish savings account
• $3,000 in another foreign financial account

Your combined foreign balances would be $11,000, which could trigger an FBAR filing requirement.

FBAR is separate from your federal income-tax return.

That catches many taxpayers by surprise because they may correctly file Form 1040 and still miss a separate FinCEN filing obligation.

FATCA and Form 8938

FATCA creates another layer of foreign-asset reporting.

Certain taxpayers must file Form 8938 with their U.S. tax return when specified foreign financial assets exceed applicable thresholds.

The thresholds are generally higher for Americans who qualify as living abroad than for taxpayers living in the United States.

FBAR and Form 8938 are not the same thing.

They overlap, but they have different rules, different thresholds, and different definitions of reportable assets.

Some Americans abroad have to file both.

This is one reason foreign-account compliance deserves attention even when little or no U.S. income tax is actually due.

Self-Employment Can Be Especially Complicated Abroad

Self-employed Americans should pay particular attention to Social Security taxes.

The FEIE can reduce or eliminate U.S. federal income tax on qualifying earned income, but it generally does not eliminate U.S. self-employment tax.

That can create a significant issue for freelancers, consultants, and business owners.

Spain and Mexico also differ substantially here.

The United States has a Social Security totalization agreement with Spain.

These agreements are designed to prevent workers from paying Social Security taxes into two countries’ systems on the same earnings.

Depending on the circumstances, a self-employed American in Spain may be able to pay into one system instead of both.

Mexico is different.

The United States currently has no effective Social Security totalization agreement with Mexico.

For a self-employed American living and working in Mexico, that creates the possibility of having U.S. self-employment tax obligations while also facing Mexican social-contribution requirements.

For remote workers and business owners, this difference alone can materially affect the cost of choosing Mexico versus Spain.

Do Not Forget Your Former U.S. State

Another frequently overlooked issue is state taxation.

Moving overseas does not necessarily mean your former state stops considering you a resident.

States determine residency under their own rules, and some are more aggressive than others.

Keeping strong ties to your former state may create problems.

Examples can include:

• Maintaining a permanent home
• Keeping a state driver’s license
• Remaining registered to vote
• Keeping significant business ties
• Maintaining other indicators that the state remains your domicile

Even if you successfully terminate residency, income sourced to that state may remain taxable.

For example, rental income from property located in California may still be taxable by California even if you have permanently moved to Spain.

For people planning an international move, establishing domicile correctly before leaving the United States can therefore be an important part of the planning process.

Tax Residency Is the Key Question Abroad

Once the U.S. side is understood, the next major question is:

Does your new country consider you a tax resident?

This matters because tax residents are often taxed on worldwide income, while nonresidents may be taxed only on income sourced within that country.

Spain and Mexico provide an excellent example of why you should never assume that every country uses the same residency rules.

Spain: The 183-Day Rule Matters

Spain generally considers an individual a tax resident when certain tests are met.

The most familiar is the 183-day test.

If you spend more than 183 days in Spain during the calendar year, you may generally be considered a Spanish tax resident.

But the analysis does not stop there.

Spain may also look at whether your primary economic interests are located there.

Spain may also presume residency when a spouse and minor dependent children habitually reside in Spain.

Another important feature is that Spain generally does not use a simple part-year residency system for individuals in the same way some taxpayers expect.

You may be classified as resident or nonresident for the tax year depending on the applicable tests.

That makes the timing of a move potentially very important.

Mexico: The 183-Day Rule Is Not the Main Test

Mexico is where many Americans get confused.

You will often hear people say:

“If I stay in Mexico fewer than 183 days, I am not a Mexican tax resident.”

That is an oversimplification.

Mexico’s domestic tax residency rules focus heavily on where you have established your home and where your center of vital interests is located.

If your only permanent home is in Mexico, that can be extremely important to the residency analysis.

If you maintain homes in multiple countries, Mexico may examine where your economic and professional life is centered.

Factors can include where the majority of your income comes from and where your main professional activities take place.

The key distinction is therefore:

In Spain, watch your days.

In Mexico, watch your home and your economic life.

Understanding this difference is critical because tax residency can determine whether Mexico or Spain taxes only your local income or your worldwide income.