Special Series · Part VI · Oct 2026
Fifty Years of the Tax Constitution (VI): False Interpretative Laws, Extraordinary Contributions and Regulatory De-legalisation (2019–2026)
Phase V (2019–2026): the reaction against false interpretative laws, extraordinary contributions and regulatory de-legalisation
José Avilez Ogando1. Combating false interpretative laws and the protection of Article 103(3)
In the most recent period (2019–2026), once the acute phase of financial adjustment had ended, the case law of the Constitutional Court focused on curbing legislative and regulatory expedients designed to circumvent taxpayers' constitutional guarantees.
The first major field of intervention lay in countering so-called false interpretative laws. Prevented from enacting ostensibly retroactive taxes by the rule contained in Article 103(3) of the Constitution, the ordinary legislature frequently resorted to passing tax provisions under the formal label of interpretative laws, invoking the general rule of Article 13 of the Civil Code to retroact their effects to the date of entry into force of the interpreted statute, thereby altering the outcome of pending disputes or overriding consolidated case law favourable to taxpayers.
The reaction against this disguised retroactivity began to take shape in Ruling no. 395/20171 — which warned that unfavourable interpretative laws “frustrate [the] citizens' legitimate expectations in the legality, adversarial fairness, and justiciability of their relationship with the law” — and was affirmed by the Plenary in Ruling no. 751/2020, of 16 December 20202. Invoking the constitutional reserve of the judicial function, the Court held that, in tax matters, “the retroactivity inherent in interpretative laws is necessarily substantive”, declaring with general binding force the unconstitutionality of unfavourable tax rules enacted under the guise of interpretative legislation. Subsequently, in Rulings nos. 121/2023 and 503/2024 — alongside the censure of express retroactivity in instantaneous taxable events in Ruling no. 658/20243 — the Plenary introduced a restrictive inflection in this case law: while keeping false interpretative laws under the automatic prohibition of Article 103(3) of the Constitution — that is, “all innovative norms to which the legislature, abusing their qualification as interpretative, seeks to attribute authentically retroactive effect” outside the hermeneutic canons permitted by the original text — the majority of the Court held that genuinely interpretative laws (which settle a prior controversy by opting for one of the plausible readings of the earlier statute) fall outside Article 103(3) and are reviewable solely in the light of the principle of protection of legitimate expectations (Article 2 CRP), a standard under which it declined to hold unconstitutional the rule reviewed in Ruling no. 121/2023, but declared unconstitutionality with general binding force in Ruling no. 503/2024 in view of the frustration of previously uniform case law.
2. The erosion of temporality in extraordinary contributions and sectoral levies
The second turning point concerned the erosion of the temporal foundation of extraordinary financial contributions and sectoral levies, a phenomenon associated with the expansion of a veritable “parallel tax State” fed by paracommutative tributes. Various charges created during the Economic and Financial Assistance Programme (2011–2014) or in its immediate aftermath with an expressly transitory or sectoral character — such as the Extraordinary Contribution on the Energy Sector (CESE), alongside other sectoral impositions (to which the Banking Sector Solidarity Surcharge — ASSB — was later added in 2020, promptly disqualified by the Court as an unconstitutional true tax in Rulings nos. 477/2025 and 478/2025 — see /posts/the-fall-of-the-banking-sector-solidarity-surcharge and /cases) — were successively maintained or renewed, year after year, by annual State Budget Laws, transforming in practice into permanent components of public revenue. Whereas in Ruling no. 7/2019 the Constitutional Court had accepted the initial validity of the CESE as a crisis levy grounded in diffuse group equivalence, the passage of more than a decade and the successive renewal of the charge in annual budget statutes profoundly altered the assessment of its constitutionality, compelling the Court to move from static review of the original text to dynamic review of the temporal persistence of the tribute's normative scope.
The exhaustion of the “extraordinary” label was demonstrated in the first major finding of unconstitutionality on the subject, Ruling no. 101/2023, delivered by the 3rd Section on 16 March 2023 (notwithstanding the divergence subsequently opened in the 2nd Section by Ruling no. 296/2023)4. In that first judgment, the Constitutional Court held unconstitutional the provisions extending the CESE to natural gas sector concessionaires, ruling that the legislative reconfiguration of the Sustainability Fund's priorities “[precludes] establishing the necessary nexus between such public services and the group of taxable persons”, since the discretionary allocation of proceeds to pay down electricity sector tariff debt entailed financing “public services of which natural gas sector operators cannot, as has been seen, be presumed to be either the cause or the beneficiaries”.
The problem of the erosion of the temporal foundation was likewise debated by the Plenary in Rulings nos. 324/2024 and 325/2024 — which, by a narrow seven-to-six majority, still upheld the levy in respect of the 2018 tax year — and by the 3rd Section in Ruling no. 244/2025 (which still validated the levy in respect of 2015)5. In the latter judgment, the Court recalled that merely repeating the label of the contribution's extraordinary character in the annual budget law does not suffice to establish its exceptionality, making it necessary to verify whether “its continued existence is justified by the persistence of the exceptional problem to which it responds; or whether, conversely, at some point it turned into a revenue-raising instrument serving other general financing needs”. Without continuous and rigorous demonstration of a just group-commutative cause, the indefinite prolongation of sectoral levies transmutes the contribution into an atypical tax that violates the principle of equality, in its dimension of group equivalence, and the ability-to-pay principle (Articles 13 and 104 CRP).
3. The curb on regulatory de-legalisation and the guarantee regarding statutory presumptions
Finally, this phase was also marked by enforcement of the reserve of formal statute against the phenomenon of regulatory de-legalisation in tax matters. The proliferation of governmental ministerial orders (portarias) and regulations issued by regulatory agencies purporting to define essential elements of fees and contributions — such as criteria for calculating the taxable base, the setting of exemptions, or the approval of rate modulators — met with firm censure from the Constitutional Court. Building on the orientation established in Ruling no. 539/2015 (in the evolution initiated by Ruling no. 152/2013), according to which the lack of parliamentary approval of a general regime does not prevent the Government from creating individualised financial contributions by decree-law, the most recent case law has clarified the reach of the prohibition of de-legalisation.
In this vein, the case law consolidated in Rulings nos. 152/2022, 243/2023, 722/2024, and 366/20266 affirmed that, in the absence of a parliamentary general regime, shaping the essential elements of financial contributions is subject to a strict reserve of primary legislative function, barring the Government from de-legalising their definition and delegating it, by blank cheque, to ministerial orders or administrative regulations. Addressing the Postal Regulation Fee regulated by governmental ministerial order in favour of ANACOM, the Plenary stressed that, in the absence of a general regime, it is required that “the essential elements of financial contributions be defined by a legislative act of Parliament or of the Government”, censuring the “encroachment by administrative power upon a domain that the constitutional order reserves to legislative power” (Articles 165(1)(i) and 266(2) CRP). Similarly, in Ruling no. 366/2026, delivered by the 1st Section on 21 April 2026 concerning high value-added activities under the Non-Habitual Resident (RNH) regime in Personal Income Tax (IRS), the Court held unconstitutional both the referring statutory provision of Article 72(10) of the CIRS (for violation of Articles 103(2) and 112(5) CRP) and the regulatory rule itself in Ministerial Order no. 12/2010, as amended by Ministerial Order no. 230/2019 (for violation of Articles 103(2) and 165(1)(i) CRP), condemning the fact that the statute, in a matter that “demands a politico-legislative choice”, “leav[es] normative shaping to the Administration” and “confer[s] upon the administrative function — by means of a ministerial order — the power, with external efficacy, to interpret, supplement, modify, suspend, or repeal”.
In parallel with the reserve of legislative function, with regard to presumptive methods for determining the taxable base, the Plenary declared with general binding force, in Ruling no. 348/20257, the unconstitutionality of the irrebuttable presumption contained in Article 44(2) of the CIRS. The Court concluded that fixing the taxable base without any possibility of proof to the contrary entails the “taxation of gains (capital gains) not actually realised”, departing from the rule of Article 73 of the General Tax Law (LGT) and colliding with the ability-to-pay principle (Articles 13 and 103(1) CRP), so that all tax incidence presumptions must admit rebuttal.
Notes
Institutional Note: José Avilez Ogando heads the Tax Law and Tax Litigation practice at Seabra, Cunha, Távora e Associados, S.A., R.L., and is a PhD Researcher at the NOVA Tax Research Lab (NOVA School of Law). Dedicated research streams on the Fiscal Constitution and taxpayers' fundamental rights are available at /research/fiscal-constitution-and-fundamental-rights and annotated case law at /cases. For representation and counsel in tax and constitutional litigation, contact via /contact.