How to File Your Spanish Tax Return (Modelo 100) as a UK Expat

Filing a Spanish tax return for the first time is one of those moments that convinces most expats they need professional help. The good news is that for straightforward situations, Modelo 100 is not as complicated as it appears. The bad news is that a “straightforward situation” for a UK expat in Spain often involves things that make it considerably less straightforward: UK pension income, rental properties, Modelo 720 overseas asset declarations, and the question of which country you are actually tax resident in.

This guide covers the basics. For anything involving property sales, complex UK income, or the Beckham Law, get professional advice.

Who Has to File a Spanish Tax Return

You must file a Spanish tax return (Modelo 100) if you are tax resident in Spain and any of the following apply:

• Your income from a single employer in Spain exceeded €22,000 in the tax year
• Your income came from more than one source and the total exceeded €15,000
• You received any rental income, capital gains, or investment income
• You are self-employed in Spain
• You receive a UK state pension or private pension paid to your Spanish account

You are generally considered tax resident in Spain if you spend more than 183 days per year in the country, or if your main economic or family interests are based here.

If you are on the Non-Lucrative Visa you are almost certainly tax resident in Spain from your first full year of residence.

Key Deadlines

The Spanish tax year runs from 1 January to 31 December, in line with the calendar year.

The filing window for Modelo 100 opens in April each year and closes on 30 June. For the 2025 tax year, you would file between April and 30 June 2026.

If you owe tax and want to pay in instalments rather than a lump sum, you must indicate this when you file rather than after. The first instalment is typically 60% on filing, and the remaining 40% in November.

Missing the deadline triggers automatic late filing penalties, so mark it in your calendar for your first year.

How to File: Your Options

Option 1: File Yourself via the AEAT Website

The Spanish Tax Agency (Agencia Tributaria, known as AEAT) has an online filing system called Renta WEB. It is only available in Spanish, which is the main barrier for most expats.

You will need your NIE number, your TIE card, and your Cl@ve PIN or digital certificate to log in. If you do not have a Cl@ve PIN yet, getting one should be a priority when you register at your local tax office (delegación de AEAT).

The system pre-populates income data it already knows about, such as Spanish bank interest and employment income reported by your employer. UK income sources, rental income, and overseas assets are not pre-populated and must be entered manually.

For a simple situation (Spanish employment only, no overseas income, no rental properties) this is manageable. For anything more complex, it becomes error-prone without Spanish language and tax knowledge.

Option 2: Use a Gestor

A gestor is a Spanish administrative professional who handles tax, social security, NIE applications, and other bureaucratic processes. They are not the same as a tax lawyer or accountant, but for Modelo 100 filing they are usually the right level of expertise and the most cost-effective option.

Expect to pay roughly €80 to €200 for a gestor to file a straightforward Modelo 100 for a non-resident with UK income. The cost increases with complexity.

For expats not confident in their Spanish and not yet fully settled into the system, using a gestor for the first year or two makes sense while you learn how things work.

Option 3: Use a Specialist Expat Tax Advisor

For more complex situations, particularly those involving UK pension income, property sales, or the interaction between Spanish and UK tax obligations, a specialist firm focused on UK-Spain taxation is worth the higher cost.

Firms like Blevins Franks work specifically with British expats in Spain and understand both tax systems well. The cost is higher than a local gestor but you are paying for expertise in the specific complications that affect UK nationals.

Blevins Franks: British expat tax advice in Spain

What You Need to Declare

As a Spanish tax resident, you are required to declare your worldwide income. This includes:

• All Spanish income (employment, self-employment, rental income, bank interest)
• UK state pension
• UK private or occupational pensions
• UK rental income (income from property you still own in the UK)
• Dividends and investment income from UK or other overseas accounts
• Capital gains from asset sales anywhere in the world

The UK-Spain Double Taxation Treaty means you are not generally taxed twice on the same income, but you must still declare it. The treaty determines which country has taxing rights over different income types.

UK government pensions (civil service, military, NHS, teaching, police) are taxed only in the UK under the treaty, not in Spain, but must still be declared on Modelo 100 as exempt income.

Modelo 720: Overseas Asset Declaration

Modelo 720 is a separate annual declaration (not a tax return) that Spanish residents must file if they hold overseas assets worth more than €50,000 in any of three categories: bank accounts, investments and securities, or real estate.

The deadline for Modelo 720 is 31 March each year, which means it comes before Modelo 100.

If you have UK bank accounts, UK investments, or a UK property you still own, you almost certainly need to file Modelo 720 as well as Modelo 100. The penalties for late or incorrect Modelo 720 filings have historically been severe, though they have been revised down following a European Court ruling.

See our dedicated guide to Modelo 720 for UK expats for more detail on what to declare and how.

Common Mistakes to Avoid

Assuming your UK income is not taxable in Spain. Most UK income (pensions, rental, investments) is either taxable in Spain or must be declared as exempt income. Not declaring it is not the safe option.

Missing the Modelo 720 deadline. It falls before Modelo 100 and catches people by surprise in their first year.

Assuming the double taxation treaty makes everything simple. The treaty prevents double taxation but does not eliminate your Spanish tax liability. Get the distinction clear before you file.

Using a general Spanish gestor for complex UK-Spain situations. A local gestor is great for Spanish-source income but may not be familiar with the treaty provisions that affect UK expats. For anything involving UK pension income or UK property, use someone with specific cross-border experience.

The Bottom Line

If you are newly resident in Spain as a UK national, your first Modelo 100 filing is worth getting right with professional help. The cost of a gestor or specialist advisor is far lower than the cost of correcting errors or paying late penalties.

Once you understand your situation and it does not change significantly year to year, you can reassess whether to continue using a professional or file yourself.

Blevins Franks: specialist UK-Spain tax advice

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*Affiliate disclosure: The Blevins Franks link in this article is an affiliate link. If you use their services through this link, I may receive a commission at no extra cost to you. I recommend them because they are among the most established specialists in UK-Spain taxation, not because of the affiliate arrangement.*