Since 1965, we’ve helped American expats navigate their U.S. tax obligations—no matter where they live or where their income comes from. In our websites you will find information on who needs to file, what deductions are available, deadlines, and much more whether you live in Spain, Portugal, or anywhere else in the world.

All our clients get automatically an extension through October 15 because we submit for all of them IRS Form 4868.

Filling a tax return is always good for you. It’s your way of telling the government how much you earned, determining whether you’ve paid your dues and figuring out if you owed any money back. Any taxpayer might even benefit from filing a tax return when s/he is not required to, thanks to refundable tax credits.

Filing from abroad comes with unique challenges and that is why many expats find these extensions essential:

• More Complex Tax Situations: Expats often deal with foreign income, local tax obligations, and U.S. tax rules like the Foreign Earned Income Exclusion (FEIE) or tax treaties—all of which can complicate your filing.
• Delayed Access to Documents: Many countries don’t issue tax documents until after April 15, making it difficult to file on time.
• Life Happens: Sudden relocations, personal matters, or work pressures can all delay your ability to file.
• Avoiding Costly Mistakes: Rushing your return can lead to errors—and those can lead to audits, fines, or additional penalties.

At US Tax Consultants, helping clients understand and manage these cross-border tax obligations is one of our core priorities. It’s exactly why our clients trust us — because we know how to keep them compliant, protected, and informed on both sides of the Atlantic.

Dual filing obligations

Even though Spain/Portugal and the U.S. have a bilateral tax treaties to avoid double taxation, the filing requirements remain. You don’t get out of filling in one country just because you file in the other.

• In the U.S., if you have foreign financial accounts or assets above certain thresholds, you may need to file FBAR (FinCEN Form 114) and Form 8938 (FATCA).
• In Spain, if you hold more than €50,000 in foreign assets, you might be required to file Modelo 720.
• In Portugal if you have a Bank abroad you must report it in the IRS3 (individual Tax Return in Portugal).

At US Tax Consultants, one of our main goals is helping our clients avoid unnecessary stress and penalties by taking proactive steps with their tax filings. Clients trust us because we understand the system on both sides — not just the forms, but the strategy behind when and how to file.

Final Thoughts

Filing both the Modelo 100 in Spain or IRS3 in Portugal and Form 1040in the USA isn’t just a bureaucratic headache — it’s a legal requirement for many dual taxpayers. Whether you’re an American living in Spain or Portugal, an expat with U.S. income, or somewhere in between, you need a clear tax strategy.

This is exactly where US Tax Consultants comes in. With deep expertise in international tax compliance, we guide our clients through every step — minimizing risk and optimizing outcomes.

Have questions? If you live in Spain here is how to make cross-border taxes simpler, if you live in Portugal, you should use this other link.

Please call us to our central office in Madrid +34 915194392 or book a free consultation for Spain, or a free consultation for Portugal.