The New Portugal–UK Tax Treaty: What It Means for Expats in 2026

Living between Portugal and the United Kingdom is one of the most appealing lifestyle configurations in Europe right now - a London career managed from the Algarve,  Porto or Lisbon, a pension drawn in sterling and spent in sunshine, a property portfolio spanning both countries.

But sooner or later, one question rises above all others: where am I actually taxed?

In September 2025, the answer changed significantly. The signing of the new Convention for the Elimination of Double Taxation between the United Kingdom and Portugal is more than a routine update, it's a wholesale modernization of the fiscal relationship between the two countries. The previous treaty dated back to 1968.

This guide explains what's new, what it means for you in 2026, and what decisions you should be making right now.

Why This Treaty Matters
The 1968 agreement was drafted in a different era, before the digital economy, before Brexit, and before the OECD's modern standards for tax transparency. The new Convention was signed in London on 15 September 2025 and entered into force on 29 December 2025. Its practical effects kicked in at the start of 2026.

Its core objectives:

- Eliminating double taxation, ensuring you aren't taxed on the same income in both countries
- Providing certainty, clearer rules for residency, business profits, and capital gains
- Strengthening cooperation, enhanced information sharing between HMRC and the Autoridade Tributária (AT)

For those with lives spanning both countries, the "guesswork" is being replaced by a more structured, and more rigorous, system.

2026 Effective Dates

Portugal

- Withholding taxes: Effective for events on or after 1 January 2026
- All other taxes: Effective for taxable periods beginning on or after 1 January 2026

United Kingdom

- Withholding taxes: Effective for amounts paid or credited on or after 1 January 2026
- Income Tax and Capital Gains Tax: Effective for years of assessment beginning on or after 6 April 2026
- Corporation Tax: Effective for financial years beginning on or after 1 April 2026

Determining Tax Residency: The Tie-Breaker Rules

Under Article 4, residency is the foundational concept, it determines which country has primary taxing rights over your income. Many moviinn® clients technically satisfy residency criteria in both the UK and Portugal simultaneously. When that happens, the Convention acts as the referee.

The tie-breaker is applied hierarchically:

1) Permanent home: Where do you have a dwelling available to you at all times?
2) Centre of vital interests: Where is your life actually happening? This includes your family, primary bank accounts, social ties, and professional activities.
3) Habitual abode: Where do you physically spend more of your time?
4) Nationality: As a final fallback, your passport determines the outcome.
The practical takeaway: residency is reflected in your actions, not just your intention. In 2026, establishing a clear "centre of vital interests" in your target country is the most important fiscal step you can take.

Real Estate: The 365-Day Look-Back Rule

Under Article 6, income from real estate is generally taxed where the property is located. No change there.

But Article 13 introduces an important new rule for investors. If you sell shares in a company that derived more than 50% of its value from real property at any point in the 365 days before the sale, the country where that property sits now has the right to tax the gain.

This anti-avoidance measure targets the use of corporate structures to sidestep local property taxes. If you hold Portuguese or UK property through a company or holding structure, a review is now a priority for the 2026 fiscal year.

Business Profits and Permanent Establishment

For entrepreneurs and company owners, the threshold for tax liability in either country is the "Permanent Establishment" (PE). Under Article 7, profits are taxable only in your country of residency, unless you operate through a PE in the other country.

New rules under Article 5

- The 12-month rule: A construction site or building project constitutes a PE only if it lasts more than 12 months.
- Anti-fragmentation rules: Prevent companies from avoiding a taxable presence by splitting activities across related entities.
- Dependent agents: If an individual in Portugal habitually concludes contracts on behalf of a UK company, that company may have a taxable presence in Portugal.

The 183-Day Rule for Remote Workers

If you've relocated to Portugal but still work for a UK employer, Article 14 is the one to understand.

Generally, you're taxed where you physically perform the work. But you may remain taxable only in your country of residence if all three of the following apply:

- You spend fewer than 183 days in the other country in any rolling 12-month period (updated from the old "fiscal year" standard)
- Your salary is paid by an employer not resident in that other country
- The salary is not borne by a permanent establishment of that employer in the other country

The 2026 reality: if you move to Portugal permanently, you will likely become a Portuguese tax resident from day one. This requires upfront coordination with your UK employer around social security and income tax obligations.

Dividends, Interest, and Royalties: Reduced Withholding

One of the most tangible improvements of the new Convention is the reduction in withholding rates on cross-border income flows.

Dividends (Article 10)
- General rate capped at 10%
- 0% for qualifying parent companies holding at least 10% of capital for an uninterrupted year

Interest (Article 11)
- Generally capped at 10%
- Reduced to 5% for interest paid to regulated banks
- Fully exempt for payments to government entities

Royalties (Article 12)
- Capped at 5%
- Definition narrowed: payments for the use of industrial, commercial, or scientific equipment are no longer treated as royalties

Pensions: Clarity for Retirees
Article 17 provides much-needed certainty for the UK retirees who form a significant part of our client base.

- Private pensions: Generally taxable only in your country of residence. If you live in Portugal, your UK private pension is taxed in Portugal, at progressive rates between 12.5% and 48% for the 2026 fiscal year.
- UK State Pension: Also taxable in Portugal as country of residence.
- Government service pensions: Article 18 maintains a crucial exception.
Pensions from UK civil service, local authorities, and similar public bodies remain taxable in the UK. This is a key distinction for former public sector workers.

What about IFICI?

While Portugal's original NHR regime closed to new applicants in 2024, the new IFICI (Incentive for Scientific Research and Innovation) regime offers a flat 20% rate on qualifying professional income. However, IFICI does not generally apply to passive pension income. For retirees, the treaty's residency protections, not IFICI, are the primary planning tool.

Trusts and Fiduciary Structures

For high-net-worth individuals using UK trusts for estate planning, Article 20(2) introduces welcome clarity. Payments made to Portuguese residents from income received by UK trustees retain their original character, so dividends paid through a trust are treated as dividends, and any tax paid by the trustees is treated as if paid by the beneficiary. This makes the application of tax credits far cleaner.

Mandatory Binding Arbitration

Historically, disputes between tax authorities could leave a taxpayer caught in double-tax limbo for years. The new Protocol addresses this directly. If a dispute concerning permanent establishments, business profits, or associated enterprises is not resolved within three years, the taxpayer can request binding arbitration. An independent panel will deliver a final decision,  giving clients a guaranteed resolution timeline.

Anti-Abuse Rules: The New Standard for Substance

The 2025 Convention introduces the "Principal Purpose Test" (PPT) under Article 27. If a structure is created primarily to gain a tax benefit from the treaty, authorities can deny that benefit. Substance and genuine purpose are now mandatory, this is not a minor technical addition.

Article 24 (Exchange of Information) has also been expanded. HMRC and the Autoridade Tributária now share data under the "foreseeably relevant" standard, including bank and beneficial ownership information. Bank secrecy is no longer a viable shield.

What This Means for You: Action Points by Profile

If you're relocating from the UK to Portugal

Focus on residency timing. Document your social, economic, and family ties in Portugal clearly and early. The tie-breaker rules will look for evidence of where your life is actually happening.

If you're a remote worker

Audit your permanent establishment risk before moving. Your UK employer needs to understand their social security and withholding obligations once you become a Portuguese tax resident.

If you're an investor

Review your holding structures against the new 365-day property look-back rule. Indirect disposals of real estate through share sales are now within the Portuguese tax net.

If you're a retiree

Understand the private/government pension distinction. Former public sector workers have a meaningfully different tax position than private pension holders under the new treaty.

Frequently Asked Questions

Will I be taxed twice if I live in Portugal and earn from the UK?

No. The Convention prevents double taxation, you'll either be taxed in one jurisdiction or receive a credit in your country of residence for taxes paid at source.

What if I spend exactly 183 days in each country?

This is a high-risk position. Authorities will apply the tie-breaker rules to determine your primary residence. The safest approach is a clear majority of presence and ties in one country.

Can the UK still tax my UK rental income?

Yes. Under Article 6, the UK retains taxing rights over property located there. Portugal will then provide a credit for UK tax paid, ensuring you're not taxed twice on the same income.

What is the Principal Purpose Test?

An anti-abuse rule under Article 27. If a structure is created primarily to benefit from the treaty, authorities can deny that benefit. Genuine economic purpose and substance are mandatory.

Get Your Cross-Border Position Right From Day One

Moving between Portugal and the UK in 2026 is no longer a simple life change, it's a multi-layered fiscal transformation. The new Convention offers real protection for those who are prepared, but it demands precision and documentation in return.
At moviinn®, we help our clients structure their move correctly from the start, assessing tax exposure, coordinating with employers and advisers on both sides, and ensuring their financial position is aligned with the new 2026 framework.

Every situation is unique. How this treaty applies to your property, pension, or business depends on the specific facts of your life, and the decisions you make now.

Book a consultation with moviinn® today.