When the Autoridade Tributária e Aduaneira (AT) opens an audit or issues an additional tax assessment against your business in Portugal, you face a tightly sequenced set of procedural deadlines and strategic choices that will determine whether you can recover overpaid tax or limit additional liability. Ferraz & Whitmore advises international companies, investment funds and cross-border groups on every stage of that process – from the first audit notification through administrative appeals, tax court proceedings and, where appropriate, mutual agreement procedures under applicable tax treaties. This page focuses specifically on audit defence and tax dispute resolution; for a broader overview of Portuguese tax law, please visit our general tax law page.
When Does a Tax Dispute Arise in Portugal?
A dispute typically crystallises at one of two points: when the AT issues a liquidação adicional (additional assessment) at the end of an audit, or when it rejects or partially accepts a taxpayer's own return. Disputes can also arise from the AT's denial of a claimed exemption or preferential regime – such as the IFICI regime, participation exemption, the IP regime (patent box) or the benefits available under the Madeira International Business Centre framework. For multinational groups, transfer pricing adjustments are a frequent trigger, often with cross-border treaty implications that require coordinated action in more than one jurisdiction.
Early identification of the legal basis for the AT's position is essential. Audit defence begins well before an assessment is finalised: Portuguese procedure gives taxpayers a right to comment on draft conclusions (direito de audição prévia), and a well-structured response at that stage can narrow or eliminate contested points before they harden into a formal assessment.
The General Assessment Limitation Period
Under Article 45 of the Lei Geral Tributária (LGT), the AT's general power to assess additional tax expires after four years from the relevant tax year. Understanding this caducidade rule is critical when evaluating the scope of an audit, the years that are genuinely at risk and whether a pending assessment has been issued in time. Separate rules may apply in cases involving fraud, failure to file or certain international structures; each situation requires individual analysis.
The Dispute Resolution Pathway in Portugal
Once an assessment has been issued, a taxpayer has a structured but time-sensitive set of options.
Administrative Claim (Reclamação Graciosa)
The first formal step is usually an administrative claim filed directly with the AT. Under Article 70 of the Código de Procedimento e de Processo Tributário (CPPT), this claim must be submitted within 120 days of the contested assessment. It is an internal review mechanism: the AT examines its own decision, and a positive outcome avoids court proceedings entirely. Where the claim is rejected or only partially accepted, the taxpayer may escalate.
Hierarchical Appeal
A recurso hierárquico (hierarchical appeal) carries the matter to the superior level within the AT's administrative structure. This step can be used either as a precursor to judicial proceedings or as an alternative where the dispute turns on administrative discretion rather than a pure point of law. It does not suspend the obligation to pay the assessed tax unless a guarantee is provided or a suspension of enforcement is obtained.
Judicial Challenge (Impugnação Judicial)
The principal judicial route is the impugnação judicial, filed before the tax and administrative courts (tribunais tributários). Decisions of the first-instance courts may be appealed to the Central Administrative Court (Tribunal Central Administrativo) and, on points of law, to the Supreme Administrative Court (Supremo Tribunal Administrativo). Litigation in the Portuguese tax courts can be protracted; understanding the realistic timeline and the evidentiary requirements before filing is part of sound pre-litigation strategy.
Tax Arbitration at CAAD
Portugal's specialised tax arbitration forum – the CAAD – offers a faster alternative for eligible disputes. Under the Regime Jurídico da Arbitragem Tributária (RJAT, Decree-Law 10/2011), arbitration is available for disputes with a value of up to EUR 10 million. Arbitrators decide strictly according to law (not equity), and decisions are generally due within six months (extendable in defined circumstances). The grounds for appeal against a CAAD award are limited, which means the decision carries significant finality. For disputes that fall within the RJAT's scope, arbitration is often the preferred route because of its speed and the quality of its specialist panels.
If you are considering which dispute resolution forum best fits your situation, our team can assess the procedural options and practical trade-offs. Please reach out at info@ferrazwhitmore.com or via our contacts page.
Cross-Border Disputes: MAP and Treaty Mechanisms
Where an assessment creates or risks creating double taxation in a cross-border context, international treaty mechanisms become relevant alongside – or instead of – domestic proceedings.
- Mutual Agreement Procedures (MAP): Most of Portugal's tax treaties include a MAP provision that allows the competent authorities of two states to negotiate an agreed resolution. MAP is typically triggered when one state's assessment conflicts with the allocation of taxing rights under the applicable treaty. The process runs in parallel with domestic proceedings and does not automatically suspend them.
- EU Arbitration Convention (90/436/EEC): For transfer pricing disputes between EU Member States, the EU Arbitration Convention provides a binding arbitration backstop if the competent authorities cannot reach agreement within the prescribed period. This instrument is separate from the CAAD and operates at the bilateral level between tax administrations.
- Directive (EU) 2017/1852 on Tax Dispute Resolution: This EU directive introduced enhanced mechanisms for resolving tax disputes between Member States, including mandatory arbitration where the mutual agreement process fails. It applies to disputes concerning the interpretation or application of agreements and conventions providing for the elimination of double taxation of income and, where applicable, capital.
Coordinating domestic litigation with MAP or EU treaty mechanisms requires careful sequencing. Concessions made or positions taken in national proceedings can affect the treaty-level process, and vice versa. Our practice covers both levels; see also our related guidance on litigation and arbitration in Portugal.
Obtaining Advance Certainty: Binding Information
Not every tax risk needs to become a dispute. Portugal's AT issues informação vinculativa (binding information), a formal ruling that binds the AT to the position it states, provided the facts submitted are accurate and the transaction is carried out as described. Seeking a binding ruling before implementing a structure – particularly one involving the IFICI regime, the patent box or cross-border financing arrangements – is a practical way to reduce audit risk at the outset rather than managing it after the fact.
Typical Pitfalls in Portuguese Tax Disputes
- Missing the 120-day window: The deadline for a reclamação graciosa under Article 70 CPPT is strict. Failing to act within this period forecloses the primary administrative route.
- Insufficient documentation at audit stage: The AT's audit teams examine transfer pricing files, substance evidence, and the factual basis for claimed exemptions. Gaps in contemporaneous documentation are difficult to remedy retrospectively.
- Underestimating the interplay of domestic and treaty proceedings: Initiating judicial proceedings without considering MAP implications can produce conflicting outcomes or exhaust procedural options prematurely.
- Choosing the wrong forum: The choice between CAAD arbitration and the impugnação judicial route is generally irrevocable once made. The decision should account for the dispute value, the nature of the legal question and the desired timeline.
- Late engagement of specialist counsel: The direito de audição prévia stage – before the assessment is finalised – is often the most cost-effective point at which to resolve or narrow a dispute.
For a more detailed procedural map, including a step-by-step guide to challenging an assessment, our analytical guide is available at Tax Audit: How to Challenge an Assessment in Portugal.
How Ferraz & Whitmore Approaches Tax Audit Defence and Litigation
Our work in this area follows a consistent methodology regardless of the size or complexity of the dispute. At the audit stage, we review the AT's information requests and draft responses that are accurate, complete and strategically considered – neither volunteering unnecessary information nor creating gaps that invite further enquiry. Where the AT's position appears to rest on a misapplication of the law or treaty, we document that analysis in writing from the outset.
At the appeal and litigation stage, we advise on forum selection, prepare the legal and factual brief, and manage procedural deadlines. For cross-border matters, we work with correspondent firms in other jurisdictions to align domestic and treaty-level strategy. Our tax disputes practice sits alongside our broader tax structuring work in Portugal, which means we understand how structures were intended to function and can explain that logic clearly to adjudicators.
We do not guarantee outcomes – tax litigation involves genuine legal uncertainty and fact-specific analysis – but we ensure that every available procedural and substantive argument is identified, assessed and deployed where it has merit.
If you or your group are facing an audit notification, have received a draft or final assessment, or are evaluating your options before a filing deadline passes, we would welcome the opportunity to discuss your situation in confidence. Contact our team at info@ferrazwhitmore.com or through our contacts page.
Sources
- International Tax Review – How to Manage a Tax Dispute in Portugal
- CAAD – Legal Regime of Tax Arbitration (RJAT, Decree-Law 10/2011)
Disclaimer: This publication is provided for informational purposes only and does not constitute legal advice. The information herein should not be relied upon as a substitute for professional legal counsel tailored to your specific circumstances. Ferraz & Whitmore assumes no liability for actions taken or not taken based on the contents of this material. For advice regarding your particular situation, please contact info@ferrazwhitmore.com.