On 29 September 2026, the Constitutional Court published Acórdão (extrato) n.º 665/2026, ruling that the interpretation of Article 78(4) and (5) of the General Tax Law (LGT) — which prevents using the official review mechanism to challenge property valuation acts underlying Municipal Property Tax (IMI) and Additional IMI (AIMI) when those acts were not timely challenged — is not unconstitutional. The decision reinforces procedural finality in property tax assessments.
Key Takeaways
- Procedural Finality Affirmed: Taxpayers must challenge property valuation acts within the legally prescribed deadlines; the official review mechanism cannot serve as a substitute for timely appeals.
- Impact on IMI and AIMI Disputes: The ruling limits the ability of property owners to retroactively correct valuation errors through administrative review, increasing the importance of monitoring assessment notices.
- Legal Certainty for Tax Administration: The decision provides the AT with greater certainty in maintaining tax rolls, as valuation acts become immune from collateral attack via the official review route after the challenge period expires.
Disclaimer: This article is compiled and summarized by the AI based on publicly available information and is for general information purposes only. It does not constitute any form of formal tax advice, legal opinion, or basis for performance. Please consult a qualified professional tax advisor or legal counsel for tax advice.
Source: Read Official Announcement