The Fair Price Score (formerly the Reality Gap Score) is HomeOS's proprietary scoring system for measuring the divergence between a Portuguese property's registered legal state and its likely actual physical condition. Scored on a scale of 0-10, it is a systematic, document-based measure available before purchase.

What the Certidao Permanente shows is legal truth. What exists in the building is physical truth.

In Portugal, these two truths frequently diverge due to informal construction, incomplete registration, inheritance chains, and licensing records that were not updated after changes.

Since Simplex 2024 (DL 10/2024), the buyer who signs the Escritura Publica inherits that gap immediately.

The Fair Price Score measures that divergence before commitment, with a score, interpretation, and action guidance before CPCV signing.

What Is the Reality Gap in Portuguese Real Estate?

The Reality Gap is the measurable divergence between what official records state and what physically exists in the property.

Every Portuguese property exists in two parallel realities.

The first is its legal reality — the record held across Certidao Permanente, Caderneta Predial Urbana, and Licenca de Utilizacao.

The second is its physical reality — what actually exists on site.

The Reality Gap is the distance between these two realities.

Where properties have been modified over time without updates, the gap can represent substantial legalisation liability under Simplex 2024.

Plantas do Imovel and Ficha Tecnica de Habitacao add context; Fair Price Score cross-references available records to estimate the size and certainty of the gap.

-> Complete guide to property due diligence in Portugal

Why Does Registered State Frequently Diverge from Actual State in Portuguese Properties?

Registered and actual state diverge because of structural licensing gaps, informal works over decades, and incomplete inheritance-era re-registration.

Factor 1: The licensing system records approvals, not changes

Licenca de Utilizacao captures approved state at a point in time, but later modifications are often not reflected automatically.

Factor 2: Decades of informal construction culture

Informal works were historically common, especially where enforcement was limited, creating systematic under-description in official records.

Factor 3: Inheritance without formal re-registration

Properties often changed hands and changed physically without complete legal record updates at IRN and AT.

Why this matters now more than it did before

Before DL 10/2024, the gap was often treated as a disclosure dispute with uncertain remedies.

After DL 10/2024, the gap acts as a direct liability transfer to the buyer at Escritura Publica.

What Are the Five Most Common Reality Gap Triggers in Portugal?

The most common triggers are balcony/terrace enclosures, mezzanines, attic conversions, pool/outbuilding additions, and kitchen/living-area extensions.

1. Balcony and terrace enclosures (varandas e terraços fechados)

The most common Reality Gap trigger in HomeOS's database. An open balcony — as approved in the original Licença de Utilização — has been enclosed with glass panels or aluminium frames, creating additional interior space. The result: the Caderneta Predial Urbana records the original floor area excluding the balcony, but the actual usable interior area includes it. The discrepancy is typically 4–15m² per enclosed balcony.

Typical legalisation cost if discovered: €5,000–€25,000 depending on size, municipal jurisdiction, and structural complexity.

2. Mezzanines and internal platforms (mezanines)

In high-ceilinged spaces — common in converted commercial units, older urban apartments, and loft-style properties — mezzanine platforms create additional floor area without being reflected in the licensed floor plan. The Caderneta records the original single-level area; the physical property has effectively 30–50% more usable space on the mezzanine level.

Typical legalisation cost if discovered: €8,000–€40,000 depending on structural intervention required.

3. Attic and loft conversions (conversão de sótão)

Converting non-habitable attic space into bedrooms, offices, or living areas is among the most significant Reality Gap triggers because the discrepancy in habitable area can be substantial — sometimes 20–40m² of additional living space that exists nowhere in the Licença de Utilização or Caderneta Predial.

Typical legalisation cost if discovered: €10,000–€60,000 depending on size and structural modifications.

4. Pool and outbuilding additions (piscinas e construções anexas)

A swimming pool added after initial construction — even one that's been there for fifteen years — requires a Licença de Construção (construction license) that may not exist. Similarly, outbuildings: garden studios, pool houses, storage structures, and garage extensions are frequently constructed without licensing. These additions appear on Google satellite imagery but not in any official document.

Typical legalisation cost if discovered: €5,000–€45,000 for pools; €3,000–€30,000 for outbuildings depending on size.

5. Kitchen and living area extensions (ampliações)

Structural extensions to the main living area — absorbing corridor space, merging a utility room, or extending into a terrace — create floor area that isn't reflected in either the Caderneta Predial or the Licença de Utilização. These can be subtle: a few square metres absorbed here, a partition wall removed there. The aggregate reality is a property meaningfully larger than its official description.

Typical legalisation cost if discovered: €12,000–€80,000+ depending on extension scope and structural works.

How Does HomeOS Calculate the Fair Price Score (0-10)?

HomeOS calculates the Fair Price Score through OCR analysis of uploaded Certidão Permanente, Caderneta Predial Urbana, and Licença de Utilização, cross-referenced with available floor-plan data.

The calculation process works in three stages:

Stage 1: Document parsing

HomeOS's OCR engine reads each uploaded document and extracts structured data: registered area from the Caderneta Predial, licensed area and configuration from the Licença de Utilização, legal description from the Certidão Permanente, and any additional data from the Ficha Técnica de Habitação (for post-2004 properties) or Plantas do Imóvel (floor plans) where provided.

Stage 2: Cross-referential analysis

The extracted data is compared across all documents simultaneously. The algorithm looks for:

• Area discrepancies (Caderneta area vs. Licença area vs. declared purchase area)
• Description mismatches (room counts, floor counts, property type designations)
• Licensing gaps (Licença issued date vs. any modifications apparent in other documents)
• Regulatory flags (EPBD class, Simplex 2024 indicators, municipal enforcement records where available)

Stage 3: Score computation

Each discrepancy found is weighted by its severity (small area gap vs. major configuration mismatch), its confidence level (clear documentary evidence vs. inferential signal), and its Simplex 2024 exposure (whether the discrepancy represents a likely obra sem licença — unpermitted work). The weighted outputs produce the 0–10 score.

Score interpretation

What the score doesn't measure

The Fair Price Score is a document-based analysis. It identifies divergences in what official records say — it doesn't conduct a physical inspection of the building's structural condition, mechanical systems, or observable defects. A building can have a low Fair Price Score (documents consistent) while having physical defects invisible to documentary analysis. The score measures the legal-physical gap specifically.

What Is the Property Risk Score and How Is It Different from the Fair Price Score?

The Property Risk Score — formerly AIRCS, Asset Integrity and Regulatory Compliance Score — is HomeOS's composite score that integrates the Fair Price Score (legal-physical divergence), energy compliance status (EPBD exposure), and full regulatory compliance posture (Simplex 2024, municipal enforcement, licensing status) into a single 0–100 measure of a property's total integrity and compliance risk. The Fair Price Score is one dimension of the Property Risk Score. The AICF — Asset Integrity Correction Factor — then translates the Property Risk Score output into a market price adjustment.

Think of the three scores as a nested system:

Fair Price Score (0–10)

Measures one specific dimension — the divergence between a property's registered legal description and its likely actual physical state. It's the Simplex 2024 liability indicator. High score = significant risk of unpermitted works that transfer to the buyer at Escritura Pública.

AIRCS (0–100)

The composite score. It integrates:

• The Fair Price Score (physical-legal divergence dimension)
• The energy compliance dimension (current Certificado Energético class, EPBD deadline exposure, estimated retrofit CAPEX)
• The regulatory compliance dimension (Simplex 2024 flags, licensing completeness, active municipal enforcement)
• Market context (absorption time, comparable transaction data, VPT-to-price alignment)

A property can have a low Fair Price Score (documents consistent — low Simplex 2024 risk) but a low AIRCS (because it's Class F with a large EPBD retrofit liability). The AIRCS gives you the full picture across all risk dimensions simultaneously.

AICF — Asset Integrity Correction Factor

The financial translation of the AIRCS. The AICF adjusts the property's declared market price to reflect the total compliance cost burden — the desconto castanho (brown discount) for energy class, the estimated Simplex 2024 legalisation liability where flagged, and the VPT reassessment risk. The AICF doesn't change the purchase price — it tells you what the price should be, given full information, and gives you the basis for negotiation.

Together, Fair Price Score + AIRCS + AICF give a buyer three complementary answers:

• How much does the physical reality diverge from the paper reality? (Fair Price Score)
• What is the total regulatory and integrity risk picture? (AIRCS)
• What should I actually pay, given everything HomeOS has found? (AICF-adjusted price)

-> Complete guide to property taxes, AICF, and true cost of ownership in Portugal

What Is "Transaction Truth vs. Asset Truth" in Portuguese Real Estate?

"Transaction truth" is what's documented in the legal records surrounding a property purchase — the declared price, the Certidão Permanente description, the licensed area. "Asset truth" is what the property actually is — its real physical extent, regulatory compliance status, energy performance, and condition. In an ideal market these would be the same. In Portugal's property market, they frequently diverge. HomeOS exists to bridge the gap between transaction truth and asset truth before you commit.

The distinction matters because most of the machinery of a property transaction is built around transaction truth. The IMT (Imposto Municipal sobre Transmissões Onerosas de Imóveis — property transfer tax) is calculated on the transaction price or VPT. The Escritura Pública records the legal description. The mortgage valuation references the declared price. The seller's representations focus on the documents.

None of this machinery automatically captures asset truth.

Asset truth is what you're actually buying. The 110m² that you'll live in, versus the 94m² registered in the Caderneta. The unlicensed pool that makes the garden unusable in summer while you're waiting for legalisation. The Class F energy rating that means your utility bills are €300/month and you're facing a mandatory €28,000 renovation before 2033. The encumbrance on the Certidão Permanente that was meant to be discharged in 2019 and somehow wasn't.

Transaction truth closes the deal. Asset truth determines whether the deal was worth closing.

HomeOS's purpose is to make asset truth visible before transaction truth is locked in. The Fair Price Score quantifies the most common form of asset truth divergence — the physical-legal gap. The Property Risk Score integrates it with the energy and regulatory picture. The AICF translates it into a financial figure. The result is a buyer who negotiates with asset truth in hand, not transaction truth alone.

This framework — transaction truth vs. asset truth — is HomeOS's operating philosophy. It's why the platform exists. And it's the reason that the four mandatory documents (Certidão Permanente, Caderneta Predial, Licença de Utilização, Certificado Energético) are necessary but not sufficient: they represent the best available transaction truth, without addressing the asset truth gap that Simplex 2024 has now made financially decisive.

What Happens When HomeOS Gives a High Fair Price Score?

A Fair Price Score of 7–10 indicates significant document-level divergence — the kind of discrepancy that suggests probable unpermitted works exist and that Simplex 2024 (DL 10/2024) liability may be material. HomeOS's recommended protocol for a high score is: do not sign the CPCV until the source of the divergence is identified and quantified; request the Plantas do Imóvel from the Câmara Municipal; and commission a physical property inspection from a specialist inspection company before proceeding.

A high Fair Price Score is not a reason to abandon a purchase. It's a reason to investigate before committing — and a strong basis for price negotiation if the investigation confirms the divergence.

Here is the recommended step sequence when HomeOS returns a score of 7 or above:

Step 1: Do not sign the CPCV yet

The CPCV is legally binding. Once signed, your deposit is at risk and your negotiating leverage drops sharply. If the Fair Price Score is high, the information needed to sign safely isn't available yet.

Step 2: Request the Plantas do Imóvel

The Plantas do Imóvel (architectural floor plans) archived at the Câmara Municipal are the most direct way to compare the licensed layout against the actual property. Request certified copies. If the seller is reluctant to support this process, that reluctance is itself informative.

Step 3: Commission a physical inspection

A physical property inspection — where a certified inspector visits the property in person — is the definitive way to verify the divergence that HomeOS's document analysis has flagged. The inspector's job is to walk the property, measure the spaces, compare the physical reality to the licensed plans, and produce a report identifying specific discrepancies and their estimated remediation cost.

InspectOS is a specialist property inspection company in Portugal that carries out exactly this type of appointment-based physical inspection. InspectOS is entirely separate from HomeOS: it's an independent company operating an on-site inspection service with certified inspectors. HomeOS identifies the risk from documents; InspectOS confirms it from the building itself. The two services complement each other — HomeOS first, InspectOS where the score warrants it.

Step 4: Get a legalisation estimate

If the physical inspection confirms unpermitted works, commission a legalisation estimate from a licensed Portuguese architect before renegotiating. The estimate gives you a specific figure — not a range — to present in price negotiation.

Step 5: Renegotiate the price or rescind

Armed with the HomeOS Fair Price Score, the physical inspection report, and the legalisation estimate, you have three options: require the seller to legalise before completion; negotiate a price reduction equal to the legalisation cost; or rescind the transaction (before the CPCV — at no cost; after the CPCV — requires the right contractual clauses).

-> Simplex 2024 Portugal: what every buyer must know about unpermitted works

Reality Gap Case Studies: Three Discoveries That Changed Purchase Decisions

Three anonymised HomeOS cases — one per common trigger type — illustrating how the Fair Price Score surfaces divergences that buyer walkthroughs, agent descriptions, and standard legal checks routinely miss.

Frequently Asked Questions