Filing in both US and Spain — what do I file?

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Answer

A retirement and remote-work corridor with regional variation inside Spain and a US filing obligation that does not end at the border. Two obligations, one income. A treaty allocates the tax; it does not consolidate the filing.

What has to be filed in each

A retirement and remote-work corridor with regional variation inside Spain and a US filing obligation that does not end at the border.

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The exception that catches people

US persons in Spain face regional rules and local property filings alongside their US return; Spanish nationals in the US face a residency exit at home.

Your next step

The full treatment — who it binds, the deadline, the penalty and the fixed fee — is on US ↔ Spain cross-border tax. Describe the situation in your own words; translating it into forms is our job.

Reviewed against current guidance for the 2025 and 2026 filing seasons by Udit Gupta, International Tax, Cross-Border Tax & Transfer Pricing Expert, Legal Quotient Consultants. Published as general information. For a position on your own file, call the 24-hour helpline.

Cross-border tax case studies

Case study 1

Building a full filing inventory for a retiree in Spain

A client who had retired to Spain was filing one income return in each country and nothing else. The work began with a schedule of every account, plan, property and holding on both sides, then a decision on each item about which return or declaration reaches it. Several disclosures had never been lodged. We brought them up to date and set out the annual list the client now works from. The engagement produced a complete inventory for the year and the omissions filed.

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Case study 2

An asset declaration that had never been lodged

A client resident in Spain had filed the income return every year but not the separate declaration about assets held outside the country, having taken the view that anything with no tax due needs no filing. We assembled the holdings as at each reporting date, lodged the outstanding declarations, and reconciled them with the income already reported. The engagement produced the missing filings and a statement of how the two obligations differ, so the next year work starts from the right list.

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Case study 3

Letting a Spanish property and reporting it in both countries

A US citizen let a flat in Spain for part of the year. The letting produced obligations attached to the property as well as the income return, and the same letting had to appear in the other country return on a different measure of profit. We prepared the local filings, rebuilt the accounts on both sets of rules, and set the relief claim on the figures actually assessed. The engagement produced reconciled letting figures and a filing calendar for the property.

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Case study 4

Two advisers, one holding, and nobody reporting it

A client used a preparer in each country and each had assumed the other was dealing with an investment holding. It appeared in neither return. We produced a single schedule listing every item and the return or declaration responsible for it, then corrected the years in which the holding had been left out. The engagement produced an agreed division of responsibility between the two advisers and a filed correction for each open year.

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Case study 5

A part-year Spanish return beside a full year abroad

A client moved to Spain in the middle of a year and wanted to know what each country would see. Spain assessed the part of the year its residence rules reached; the other country assessed the whole of it. We fixed the dates, allocated the items that straddled the move once, and used that allocation in both filings. The engagement produced two returns for the move year that agree item by item, together with the first year of asset reporting on each side.

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Case study 6

A Spanish national in America keeping a house at home

A client living in the United States had kept a house in Spain and was unsure which country return should carry it. The property location gives one country the first claim on anything it produces, while residence brings it into the other return with relief. We set out which filings the property itself creates in Spain, reported the income in both returns from a single set of accounts, and documented the position ahead of an eventual return home. The engagement produced the property own filings and a matched pair of returns.

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Case study 7

A TFSA That Costs More Than It Saves

Canadian tax-free accounts are not tax-free to a US person, and some of them carry a reporting form of their own. The file is a review of what is held, what each account triggers on the US side, and whether the account is worth keeping once the reporting is priced in.

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Case study 8

A US Citizen Settled in India, Filing on Both Sides

Residence in India and citizenship in the United States produce two annual returns for one income. The order decides the credit, and the Indian financial year and the US calendar year have to be reconciled before either is prepared.

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All case studies — every published engagement in one place.

Core International & Cross-Border Tax Services

International Tax Planning & Advisory

Strategy and compliance for income, assets and families spread across borders.

One coordinating team: filings on every side of the border are sequenced so treaty relief and foreign tax credits are claimed once — and in the right country.
U.S. & Cross-Border Tax Returns
Dual filers: U.S. citizens in Canada and Canadians with U.S. income run two parallel systems — we prepare both, in the right order, every year.
Expat & Emigration Tax
The move year is its own project: the elections and valuations filed that year decide the next decade of both countries’ returns.
Non-Resident Canadian Tax
Default withholding is 25% of gross: elective returns routinely turn over-withheld rent and pensions into refunds.
Transfer Pricing & BEPS
Documentation prepared with the return is the cheapest insurance in international tax; reconstructing it during an audit is the most expensive.
Cross-Border Estates & Trusts
Wills drafted for one country routinely misfire in the other — deemed disposition here, estate tax there, credits in between.
Cross-Border Corporate Tax
Expansion raises the same four questions every time — entity, PE, repatriation, payroll. We answer them before the tax authorities do.
India Tax for NRIs & Returning Residents
The deduction is taken on the sale price, not the gain — which is why an NRI property sale strands cash unless the certificate is applied for before closing.
Canadian Tax with a Foreign Element
Residency is decided on facts, not on a form — and the year you arrive or leave is the one where the largest amounts turn on the smallest details.
UAE Tax for Expats & Their Home Country
A zero-tax country is only half the answer — the question that decides the bill is whether the country you came from still treats you as resident.

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Software revenue is rarely taxed where the team sits. Licence, subscription and service income are characterised differently by each side, and the answer decides withholding at source, treaty relief and whether a foreign customer creates a taxable presence at all — questions that are cheap to settle before the contract and expensive afterwards.

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Asked next about US and Spain

What do I file in Spain as a US citizen living there?

Expect a Spanish resident income return and, if you hold property there, the local filings that property creates. Alongside them the return in the other country continues, because that obligation does not end when you move. The two returns report the same income and one relieves the other tax; they are not alternatives. Spanish residence also brings reporting about assets held outside the country, which is information rather than tax and is missed more often than the return itself. The work starts with a list of every filing your circumstances create, before any figures are prepared.

Do I have to report my Spanish bank accounts to the US?

Reporting about accounts and assets held outside the country sits separately from the income return, and it is triggered by holding them rather than by earning anything on them. So an account that produced almost nothing can still be reportable, and moving money between two of your own accounts does not reduce what has to be disclosed. Treat the disclosure inventory as its own exercise, built from a list of every account, plan and holding you can sign on. It is the part of this corridor that most often has to be brought up to date later.

Does Spain want to know about my assets in America?

Spanish residence brings its own reporting about assets held abroad, distinct from the income return and owed whether or not tax is due on them. People arriving from the United States commonly have accounts, an employer plan and perhaps a property, and each has to be tested against the reporting rules rather than assumed to be covered by the income return. The practical approach is one schedule of everything held on each side of the corridor, then a decision on each item about which return or declaration reaches it.

Which return should I prepare first if I file in both?

Prepare the one the treaty gives the first claim to, because the second return relief claim depends on its figures. That is usually the country of source for the income in question, and it can differ item by item within the same year, so the sequence is decided by income type rather than by which return happens to be due earlier. Where a deadline forces the second return out first, file it on a stated basis and correct it when the other assessment arrives. What you cannot do is estimate the relief and leave it there.

Is my US social security pension declared in Spain?

Payments of that kind are dealt with by a specific treaty article, and the article decides which country taxes them rather than removing them from view. Declaring the income where it is required and claiming relief in the other return is normally how it resolves. What matters for the filing is that the same payment is described consistently in both returns, because the characterisation drives which country holds the first claim, and an inconsistent description leaves each authority looking at a different item. Settle the characterisation once and use it in both.

Do I file in both countries in the year I move to Spain?

Yes, and the move year is the heaviest one. Spain assesses you for the part of the year its residence rules reach, so its return covers a period. The return in the other country covers the whole year regardless. Items that straddle the move have to be allocated once and then reported the same way in both filings. Any reporting about assets held abroad also begins in that year, on each side, and it is far easier to build the inventory while the paperwork from the move is still to hand.

What is a double tax treaty and what does it actually do?

It is an agreement between two countries that divides up the right to tax. Article by article it decides which country taxes employment income, dividends, interest, royalties, pensions, property and business profits — and where both may tax, it caps what the source country can withhold and tells the other to give credit. It also breaks residence ties and opens a government-to-government channel for disputes. What it never does is apply itself: a treaty position is claimed. See our treaty work.

What is a permanent establishment, and how easily do we create one?

A taxable presence in another country under the treaty — typically a fixed place of business such as an office, branch, factory or workshop, or a dependent agent habitually concluding contracts on your behalf. Some treaties add a services test measured in days. Purely preparatory or auxiliary activity is excluded, but that carve-out is narrower than it sounds: one senior employee working from home in the other country, with authority, has been enough. See business profits and permanent establishment.

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