Methodology
Last updated: 27 January 2026 • Version 1.0
1. Purpose
This page explains how Property Passport UK derives and presents key signals about property data completeness, verification, and freshness.
We believe in transparency: no "black box" scoring. Everything displayed on a Property Passport record is derived from known data sources, clearly labelled, and verifiable.
This methodology applies to all public-facing Property Passport records and is designed to help users understand how signals are calculated and what they represent.
2. The Completion Score
The Completion Score is a percentage (0–100%) indicating how much verified data exists for a property relative to the full set of data categories we track.
The Completion Score is not:
- A valuation or price estimate
- A quality judgement or safety assessment
- A recommendation to buy, sell, or rent
- An indicator of structural condition or legal status
It simply measures data availability. A property with a 90% Completion Score has more verified data on record than a property with a 40% score.
Important Notice
The Completion Score is indicative only. It does not imply property quality, safety, or value. All data should be independently verified before making any property-related decisions.
3. How the Completion Score Is Calculated
The Completion Score is computed using a weighted formula across data categories. Each category contributes a different proportion to the overall score based on its importance to property records.
| Category | Weight | What Counts |
|---|---|---|
| Property identity (UPRN, address) | 20% | Confirmed UPRN, validated address |
| Energy performance (EPC) | 15% | Current EPC certificate on record |
| Ownership & tenure | 15% | Title or claim verified |
| Documents & evidence | 15% | Supporting documents uploaded |
| Transaction history | 10% | Price paid records linked |
| Physical attributes | 10% | Building form, size, age confirmed |
| External data | 10% | Flood, schools, transport data available |
| Media | 5% | Photos uploaded (front elevation, etc.) |
The score is recalculated automatically whenever new data is added or updated. A property with no data may show a score as low as 10–20% (based on basic address information alone). A fully documented property may reach 95–100%.
4. Verification States
Data displayed on a Property Passport record is assigned one of four verification states. These states indicate the source and reliability of the information.
Public / Authoritative
Data sourced from official open data or authoritative registers (e.g. EPC, HM Land Registry, Ordnance Survey). This represents the highest level of confidence.
User-Provided
Information entered by the property owner or an authorised stakeholder. This data has not been independently verified by Property Passport UK or a professional third party.
Professional-Verified
Data confirmed or attested to by a professional user (e.g. surveyor, conveyancer, estate agent) acting in their professional capacity.
Disputed
Information flagged as potentially inaccurate or outdated. Disputed data remains visible but is clearly marked as under review.
Verification states are displayed alongside the relevant data section. Users are encouraged to prioritise Public/Authoritative and Professional-Verified data when making decisions.
5. Data Freshness and Timestamps
Every data section on a Property Passport record shows when it was last updated and from which source provider.
"Last updated" refers to when we last synchronised data from the source provider, not necessarily when the underlying data itself changed.
For example:
- An EPC certificate issued in 2022 may show "Last updated: January 2026" if we refreshed it from the national EPC register in January 2026.
- User-uploaded documents show the upload timestamp, not the creation date of the document itself.
We do not guarantee real-time accuracy. Data displayed on Property Passport UK reflects the most recent information available to us at the time of last synchronisation or update.
6. Confidence Scoring
Where data is matched from external sources (e.g. linking an EPC certificate to a property), we display a confidence percentage to indicate the quality of the match.
Confidence scoring works as follows:
- 100% confidence: Exact UPRN match. The data is linked directly to the Unique Property Reference Number.
- 90–99% confidence: High-quality address-based match with minor variations (e.g. postcode format differences).
- 70–89% confidence: Address-based match with some ambiguity (e.g. flat number differences, building name variations).
- Below 70%: Lower confidence match. Data may apply to a neighbouring property or different unit in the same building.
Where confidence is below 100%, users should review the data carefully and verify independently if accuracy is critical.
7. What Is NOT Included
The Completion Score and other signals on Property Passport UK do not factor in or assess:
- Property value or market price
- Neighbourhood quality or desirability
- Investment potential or rental yield
- Structural condition or safety compliance
- Legal disputes, easements, or restrictive covenants
- Planning restrictions or development potential
- Tenant behaviour or landlord performance
We do not make recommendations or provide advice. Property Passport UK is a data aggregation and presentation platform, not a valuation or advisory service.
8. Disputes and Corrections
If you believe data displayed on a Property Passport record is inaccurate, the appropriate action depends on the source of the data:
Public or Authoritative Data (EPC, HMLR, etc.)
Corrections should be made at the source provider. For example:
- EPC errors: contact the original assessor or the Department for Levelling Up, Housing & Communities
- HM Land Registry errors: contact HM Land Registry directly
- Address or UPRN errors: contact your local authority or Ordnance Survey
Once corrected at source, Property Passport UK will reflect the updated data at the next synchronisation.
User-Provided Data
The property owner or authorised stakeholder can update or remove user-provided data directly through their account.
Flagging Disputed Data
If you believe data is incorrect but cannot correct it directly, you may:
- Use the Flag feature to mark the data as disputed (if you are an authorised stakeholder)
- Contact us at support@propertypassport.uk with evidence of the error
9. Limitations
Important Limitation Notice
Property Passport UK is a data aggregation platform, not an advisory service. All data should be independently verified before making any property-related decisions.
See our Disclaimers page for full details on limitations and exclusions of liability.
Additional limitations to be aware of:
- Data completeness varies significantly between properties based on what public records exist and what owners have uploaded
- Matching algorithms may occasionally link data to the wrong property (check confidence scores)
- Historical data may be incomplete, especially for older properties
- Third-party data is subject to the terms and accuracy guarantees of the source provider, not Property Passport UK
- The Completion Score is a relative measure and may evolve as we add new data categories
10. Related Pages
For more information about how Property Passport UK works and how we handle data, please see:
- Open Data Sources — Full list of public data providers we use
- Disclaimers — Limitations and exclusions of liability
- Terms of Service — Legal terms governing use of the platform
- Privacy Policy — How we handle personal data
Property Passport UK
Transparent, verifiable property data