A recent Administrative Arbitration Centre (CAAD) ruling offers essential lessons for expats navigating Portuguese tax rules. The case focused on two issues: the taxation of capital gains and the recognition of residence under the Portugal-UK double taxation treaty.
The case in short
The taxpayer had purchased BES bonds in 2014 for €33,092.20 and sold them in 2017 for €27,880.00.
Although this was an apparent loss, the Portuguese tax authority treated it as a gain and issued a tax assessment.
In addition, the authorities included the UK employment income of €15,934.97 through an automatic declaration, claiming no return had been filed.
The taxpayer contested, showing he had been a UK resident since 2016 with a valid employment contract, UK tax filings, and tax paid abroad.
What the CAAD decided
First, regarding the bonds, CAAD confirmed that a sale below purchase value cannot generate a taxable capital gain.
The tax authority’s decision was an error of fact and law, so the assessment was annulled.
Second, regarding UK income, CAAD reviewed the taxpayer’s documents: an HMRC residence confirmation letter and a Portuguese consular certificate from London.
Together, these confirmed his UK residence between 2016 and 2020.
The tax authority argued that only the official tax residence certificate under the Portugal-UK double taxation treaty would suffice.
However, CAAD rejected this formalistic view, confirming that Portuguese law allows broader means of proving residence.
Why this matters
For expats, the ruling is highly relevant.
It shows that proof of residence does not depend on a single document.
Instead, consistent evidence, employment contracts, tax returns, or consular certificates can be enough to establish treaty residence.
The case also highlights the importance of checking capital gains carefully, since tax should never apply where there is a loss.
Key points to remember
- No legal restriction on proof of residence for treaty purposes.
- Coherent, unchallenged documentation is sufficient to demonstrate foreign residence.
- Capital gains taxation does not apply where there is a loss.
- The tax assessment was annulled, with costs charged to the authorities.
Practical guidance for expats
If you work abroad, keep contracts, proof of address, tax returns, and local tax payment evidence.
Certificates should also be obtained from local tax authorities or consulates where possible.
If you receive an automatic Portuguese assessment, check annexes G (capital gains) and J (foreign income).
Evaluate your tax residence and the treaty’s application in that year.
Seek revision or arbitration if necessary.
This article summarises a CAAD decision and does not replace individual legal advice. Each case depends on specific facts and documents.
Source: CAAD Arbitration – Process no. 1030/2024-T, decision dated July 11, 2025.
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