Electronic Building Identity (HTK) in Greece: What Property Buyers Need to Know
The Electronic Building Identity (HTK) is Greece's official electronic building-documentation system. Its Certificate of Completeness is issued through a defined procedure by an authorised engineer and is relevant to qualifying residential transfers. The existence of this certificate does not automatically prove that the property has no concealed defects or that an independent structural survey has been carried out.
Why does Greece have an Electronic Building Identity?
Ηλεκτρονική Ταυτότητα Κτιρίου (HTK) is an electronic framework for gathering relevant construction and property-unit documentation. It is administered through the Technical Chamber of Greece (TEE).
The Greek Ministry of Environment explains the system's role in property transfers and recording relevant building information. Its purpose is not to publish a property market valuation or certify legal title.
A buyer should ask whether the file actually describes the unit being purchased and whether alterations are appropriately recorded.
What can the HTK file contain?
The prescribed information depends on the property and applicable legal requirements:
| Document | Buyer relevance |
|---|---|
| Building permit and amendments | Which construction was authorised |
| Approved plans | Official layout and use |
| Records of later alterations | Why existing layout may differ |
| Unauthorised-construction declarations where relevant | What works were covered, under which scheme |
| Energy Performance Certificate (PEA) | Energy classification, not a structural survey |
| Other applicable technical reports | Compliance with the particular statutory requirement |
Older buildings may have missing archives or different documentary histories. An engineer should determine which documents are legally required and which alternative procedures, if any, are available.
A complete-looking folder is not proof that every physical discrepancy has been investigated.
Are the record, extract and certificate different?
Yes. Buyers should distinguish:
| Item | Function | Does not automatically prove |
|---|---|---|
| Electronic Building Identity | Underlying registered information | No hidden defects |
| Building Identity Extract — απόσπασμα | Output concerning the recorded identity | Clear title |
| Certificate of Completeness — πιστοποιητικό πληρότητας | Formal certificate following statutory procedure | Full structural or systems survey |
The Gov.gr certificate service specifies finalised registration, an on-site inspection and payment of the relevant fee for issuance by an authorised engineer.
The visit required for the HTK process should not be rebranded as an unrestricted inspection of the whole building's structure, wiring or plumbing.
Is HTK mandatory for an ordinary apartment transfer?
For ordinary residential property within the applicable Category II framework, the relevant Building Identity requirements arise in connection with qualifying transfers. These requirements must not be confused with separate deadlines for certain Category I special-use buildings.
The Ministry's 2026 planning-deadline announcement extended the Category I filing deadline to 1 February 2028. This is not a blanket waiver for ordinary apartment sales.
The Greek planning legislation was codified in Law 5306/2026. The notarial circular of 29 September 2026 discusses correspondences between older Law 4495/2017 references and the new numbering, and TEE platform updates.
A document bearing an older statutory reference is not automatically invalid. The notary and engineer must establish the applicable law and document status.
Whole-building or apartment-level identity?
The system accommodates building-level and separately owned property-unit records. A flat's identity should be linked to the correct unit and applicable building documents.
A certificate relating to one unit should not be presumed to establish the condition of every roof, lift or common structural element. Nor does a building-wide record automatically resolve each apartment's private alterations without examining what it covers.
Ask the engineer what exact property and records the document identifies.
Who prepares HTK and what should the buyer commission separately?
An appropriately authorised engineer handles the statutory file and certificate. The Gov.gr registration service describes authorised engineers' registration and updating access.
The seller's engineer may be preparing transfer documentation. A buyer-appointed engineer can independently assess visible condition, actual area, permits, discrepancies or specialist inspection needs. These engagements are related but not identical.
Ask for a report specifying exactly which documents were reviewed, when the property was visited and what was not assessed.
What if the drawings differ from the apartment?
An enclosed balcony, converted basement or extra room can be authorised, subject to a valid regularisation procedure, or unresolved. A declaration number alone does not tell you which.
The engineer should compare approved and current configuration, identify the construction date and available documentation, and determine the statutory consequences. The lawyer assesses the effect on transfer.
Worked example: 94 m² advertised, 80 m² documented
A fictional Athens apartment is marketed at €295,000 for 94 m². The reviewed approved plans identify 80 m² of main residential space and a 14 m² enclosure with an unverified documentary status. HTK finalisation is pending.
| Denominator | Asking-price calculation |
|---|---|
| 94 m² marketed | Approximately €3,138/m² |
| 80 m² documented main space | €3,687.50/m² |
These are asking-price ratios using different area bases, not independent property valuations. Neither establishes the legal status of the enclosure or whether that space has value. The engineer must identify what has been authorised or appropriately documented.
Fictional example.
The HTK Readiness Check
| Stage | Evidence available | Open question |
|---|---|---|
| Documents collected | Permit and drawings supplied | Complete and relevant? |
| Physical comparison | Engineer has examined current layout | Any unresolved discrepancy? |
| Declaration reviewed | Specific alteration is documented | Legal category and status correct? |
| Registration finalised | Relevant electronic information completed | Formal certificate ready? |
| Certificate issued | Statutory certificate step completed | Independent condition report needed? |
| Buyer review complete | Scope-defined findings delivered | Any remaining issue before deposit/deed? |
This is a buyer communication framework, not an official TEE progress classification.
Does HTK guarantee that a house is safe?
No. A file may include particular legally required structural or technical documentation, but its presence cannot automatically be generalised into a comprehensive building-condition warranty.
An independent survey may still need to examine cracking, moisture, corrosion, roofing, services and specialist structural concerns. The lawyer independently checks ownership and encumbrances.
The buyer should avoid phrases such as “HTK verified = everything legal and safe.”
What if the certificate is pending when the seller requests a deposit?
Ask why: missing archives, routine registration, inspection yet to occur, or a substantive discrepancy. These situations have different consequences.
The buyer's lawyer should review any deposit or reservation agreement in light of unfinished checks and explain the legally effective withdrawal and payment provisions. A future certificate is not a substitute for terms that appropriately address present uncertainty.
The Digital Property Transfer File streamlines eligible notarial transfers; it does not replace buyer-side legal or engineering investigation.
What does HTK cost?
Distinguish applicable administrative fees from the engineer's professional work, retrieval of missing records, extra drawings, technical studies and any separate statutory procedure for irregularities. There is no reliable universal total fee for every property.
Ask the seller and advisers who will arrange and pay for each required element and what happens if unexpected work becomes necessary.
Must HTK be updated after alterations?
Relevant changes and works may require updates under the applicable rules. A certificate issued before later construction is not evidence that those later works were authorised. Before undertaking renovations, ask the engineer about required permissions and record updates.
Frequently asked questions
Is an HTK certificate the same as a structural survey?
No. Its formal statutory purpose and the scope of an independent structural assessment are different.
Does an unissued certificate prove illegal construction?
No. The reason for delay must be investigated.
Does the Category I 2028 deadline apply to all apartment sales?
No. Category I filing timing and the Category II transfer framework are separate.
Can the buyer use only the certificate without the underlying plans?
That is an inadequate basis for evaluating discrepancies or physical condition. The buyer's engineer should examine the relevant sources.
The buyer's key conclusion
Do not ask only “Does this apartment have HTK?” Ask “Does its documentary record describe the exact property, which works and areas are included, and what remains unverified?”
The Greek Property Report conducts independent, buyer-funded research without broker commission or completion-based fees. It cannot replace statutory engineering work, an independent survey or legal advice.
Understand the evidence, and what still needs checking
Our methodology explains what independent, buyer-funded research can establish—and what must be verified by a Greek lawyer, engineer or notary.
Independent, buyer-funded research. No brokerage commission or fee contingent on a completed purchase. Not a professional valuation, legal opinion or engineering assessment.