It's a reasonable question, and the honest answer hangs almost entirely on the word "residence," which we'll cover below. The reassuring part is that the UK and Spain saw this coming decades ago and built a treaty specifically to stop the same euro being taxed twice. However, the treaty is not applied automatically. Getting your residence status wrong, even on one point, can result in exposure to tax in both countries simultaneously.
In the rest of this article, we'll explain how the treaty works, how to determine your tax residence, and the steps you can take to avoid paying tax twice.
Key takeaways
- The UK-Spain double tax treaty (in force since 12 June 2014, and unaffected by Brexit) prevents the same income being taxed twice by assigning taxing rights between the two countries and giving you a tax credit already paid in the other.
- The treaty taxes your freelance income in your country of tax residence, which makes establishing where you're resident, and being able to prove it, the single most important step.
Why Brexit didn't affect the treaty
It's widely assumed that Brexit dismantled all financial arrangements between Britain and the EU. Fortunately, not this one. The UK-Spain double taxation convention is a bilateral agreement between two governments, not an EU instrument, so it carried on unaffected. It was signed in 2013, came into force on 12 June 2014, and both HMRC and the Spanish Agencia Tributaria still apply it today.
What the treaty does is simple to state and fiddly to apply. It takes each type of income (your freelance earnings, dividends, rent, a pension) and decides which country gets to tax it, and where both can, it makes sure you get credit for what you've already paid, so the same money isn't billed twice. Every one of those decisions depends on which country you are a tax resident of.
Residence determines everything
Spain's test is mostly mechanical. If you spend 183 days or more on Spanish soil during a calendar year, you're a tax resident, and Spain counts any part of a day in the country as a whole day, so the arithmetic is less forgiving than people expect. Even below that line, Spain will treat you as a resident if your center of economic interests is there: your main client base, your business, your family.
The UK uses its Statutory Residence Test, which adds a day count on top of "ties" like available accommodation and work. You still get automatic residence at 183 days, but you can be caught well below that.
But there's an issue that can catch you out mid-move: the two countries don't use the same calendar. The UK tax year is from 6 April to 5 April; Spain's is the plain calendar year. In the year you relocate, it's entirely possible to satisfy both countries' domestic residence rules at once. When that happens, the choice is not yours to make. The treaty determines it instead.
When you're a resident in both countries
If you're resident in both countries under their own rules, Article 4 of the treaty sets out a series of tests, applied strictly in the order they appear. You stop at the first one that gives a clear answer:
- Permanent home. Where do you have a home permanently available to you? If that is Spain alone, the matter is settled.
- Center of vital interests. If you have a home in both countries, the tie goes to wherever your personal and economic ties are stronger: family, primary clients, and where your working life is based.
- Habitual abode. If the question remains unresolved, it comes down to where you genuinely spend most of your time.
- Mutual agreement. In the rare case that none of the above resolves it, the two tax authorities settle the matter between themselves.
For someone who has genuinely moved, the ladder usually resolves at step one or two, and it points to Spain. However, notice what every rung is really measuring: whether you've cut ties with the old country or only partly moved. If you retain a roster of UK clients and a flat available in London, you give Spain's tax authorities grounds to challenge your position.
The most important factor for freelancers
Most treaty guides devote pages to dividends and royalties. For an independent professional, the one to know covers independent personal services, and the rule is simple: your freelance income is taxable in the country where you're a tax resident. If you live and work in Spain as a Spanish resident, Spain taxes your professional earnings, including the invoices you send to clients back in the UK.
There's one exception, and it can become a problem if you're not careful. If you keep a "fixed base" regularly available to you in the other country, the textbook example being a home office you hang onto in the UK, then that country can tax the share of income tied to that base. This means that, if you try to keep one foot in each country, you can give both of them a claim on your work. The best position is a single clear country of residence, with no stray base left behind to muddy it.
Filing obligations as a Spanish tax resident
Becoming a Spanish tax resident brings filing obligations that catch newcomers off guard, and Spain takes them seriously.
- Modelo 100 is your annual income tax return, declaring worldwide income. The campaign for 2025 income lasts from 8 April to 30 June 2026.
- Modelo 720 is an informational declaration of overseas assets (foreign accounts, investments, property) that takes effect once any single category passes €50,000. It's easy to forget and has historically resulted in steep penalties.
- Wealth tax applies to residents' worldwide net assets above regional thresholds, and the treaty doesn't protect you from it.
Your certificate of tax residence is one of the documents that does a lot of the work. Spain's Supreme Court has confirmed in recent rulings that a certificate issued by another country "for the purposes of the Convention" can't be simply brushed aside by the Spanish tax authorities. If you ever need to prove which country you belong to, that certificate is what opens the door to the treaty, so get one issued for treaty purposes.
The Beckham Law
There's one more thing every high earner considering Spain should know, and it's a disadvantage for the self-employed. Spain's impatriate regime, which everyone calls the Beckham Law, lets qualifying newcomers pay a flat 24% on Spanish-source income up to €600,000 and skip Spanish income tax on most foreign income, for the year they arrive plus five more. That's a significant saving on a high day rate against standard rates that can go up to 47%.
However, the Beckham Law is largely built for employees. You generally qualify by moving to Spain on an employment contract, an intra-company assignment, or, since the 2023 Startup Law, as a digital-nomad-visa holder employed by a non-Spanish company. Standard self-employed autonomos are usually excluded, which means the single biggest tax break for incoming talent is mostly closed to people who freelance the conventional way. Eligibility turns on the fine print of your status, so consult an advisor before assuming whether you qualify.
How Hightekers can help
The treaty decides where you're taxed, the tie-breaker rewards a clean break, the freelancer's article punishes a stray base in the old country, and even Spain's best tax regime leans toward employees. Every thread points the same way: the better defined your status in your country of residence, the simpler your tax life.
But once you've moved to Spain, you still have chores to do: invoice clients, pay Spanish social security, file on time and stay compliant. You can do that as an autónomo, carrying the quarterly admin yourself, or you can let Hightekers employ you. You keep finding your own clients and setting your own rate; Hightekers becomes your legal employer in Spain, invoices your clients, runs payroll, and handles the tax and compliance behind the scenes.
The relocation payoff is a single, unambiguous country of residence and genuine employee status, rather than a half-moved freelancer clinging to fragile UK ties and a fixed base nobody can quite explain. And because Hightekers operates across Spain, France, Belgium, the Netherlands, Switzerland, and the UAE, the same holds wherever your move lands. It won't turn you into a tax expert, and it's no substitute for advice on your situation, but it removes most of the moving parts that make cross-border freelancing go wrong.
What to do before you relocate
If you take one thing from all this, make it the order of operations. Pin down your residence first, because every other answer flows from it. Get a certificate of tax residence issued for treaty purposes, so you can prove your position if anyone asks. Take proper advice on the Beckham regime before you assume it's open or closed to you and decide, deliberately, how you'll operate once you land.
The same euro shouldn't be taxed twice. The treaty makes sure of that. Your job is to give it a clear enough picture to do so.
Thinking about freelancing from Spain and want the tax side handled properly from day one? Hightekers can employ you in Spain, manage your payroll, social security, and compliance, and show you what your take-home is before you commit. Tell us about your situation, and we'll run the numbers.
FAQ
Does the UK-Spain double tax treaty still apply after Brexit?
Yes. It's a bilateral agreement between the two governments, so Brexit didn't affect it. It has been in force since 12 June 2014, and both HMRC and Spain's tax agency still apply it.
If I freelance from Spain for UK clients, where do I pay tax?
Under the treaty's rule for independent services, your freelance income is taxed in your country of tax residence. If you live in Spain as a Spanish tax resident, Spain taxes that income even on invoices to UK clients, though a credit prevents you from being taxed twice on anything the UK also taxes.
Can I be a tax resident in both the UK and Spain at the same time?
You can meet both countries' domestic residence rules at once, especially in the year you move, because their tax years don't align. When that happens, the treaty's tie-breaker rules (permanent home, then center of vital interests, and so on) decide which country wins for tax purposes.
Does the treaty mean I only pay the lower of the two countries' taxes?
No. It prevents double taxation by giving you a credit for tax paid in the other country, but you effectively pay the higher of the two rates, not the lower.
Can freelancers use Spain's Beckham Law?
Usually not. The regime is mainly for people moving to Spain on an employment contract or assignment, and since 2023, certain digital-nomad-visa holders employed by a non-Spanish company. Standard self-employed autónomos generally don't qualify, so check your eligibility carefully.
