You have owned an apartment for many years or inherited it. Suddenly, a notary, a bank or an engineer asks whether the approved plans correspond with the property’s actual condition. Does the glazed-in balcony, converted storeroom or attic turned into living space hinder a sale, donation or renovation?

In Greece, unauthorised construction or an unauthorised change of use is called afthaireto (αυθαίρετο), with the plural afthaireta. The person who carried out the work may bear responsibility, but the current owner must address the property’s outstanding planning status, whether they bought or inherited it.

Quick answer: what is the position in 2026?

  • Eligible unauthorised construction and changes of use may be regularised through an engineer. The procedure involves supporting documents, fees and, where applicable, a fine. Regularisation is not the same as obtaining a legalisation permit.
  • The ordinary regularisation framework concerns unauthorised works or changes of use completed before 28 July 2011, subject to eligibility conditions and exclusions.
  • The deadline for eligible Category 1 to 4 submissions is 31 March 2028. The extension was introduced by Article 43(4) of Law 5270/2026, Government Gazette A΄ 9/23 January 2026. karagilanis.gr
  • Transfers involving unresolved unauthorised construction or specified planning violations are generally prohibited, subject to statutory exceptions.

The framework commonly referred to as Law 4495/2017 has since been incorporated into the Spatial Planning and Urban Planning Code, Law 5306/2026. Your engineer should use the current provisions and amendments when assessing the property. hellenicparliament.gr

What counts as an unauthorised change?

Construction carried out without the required permit, contrary to the permit or beyond its approved scope may constitute an unauthorised alteration. Using a space differently from its authorised use may also create a planning violation.

Examples include lofts, attics, basement storage converted into living space, pools, extensions, parking alterations and changes from auxiliary to main use.

Two points surprise overseas owners:

  • The issue remains with the property after a purchase or inheritance. Being unaware of the work does not resolve its planning status.
  • Small changes can still matter. Classification and cost depend on the type, extent, date and other circumstances of the alteration, rather than size alone.

In a polykatoikia, or Greek apartment building, common parts and other owners’ rights may also be involved.

What are common examples?

  • Enclosed or glazed balconies and covered terraces.
  • Mezzanines and added floors.
  • Attics or basements converted into living space.
  • Internal layouts that differ from approved plans.
  • Parking spaces that differ from the permit.
  • A change of use, such as storage to residential.

These examples require assessment. A difference from an old drawing does not automatically mean that the work is unlawful or that the same regularisation procedure applies in every case.

Why do owners only find out at the worst moment?

The issue often surfaces when something else needs to happen:

  • A sale: The engineer’s assessment and the documents required for the transfer may reveal undeclared deviations.
  • An inheritance or gift: Our guide to inherited property in Greece covers the wider first year.
  • A renovation: An engineer or contractor may notice that the property differs from the drawings.
  • A mortgage: The lender’s legal or technical checks may raise questions.
  • A Cadastre or E9 review: Comparing records may reveal discrepancies. See our guides to checking the Hellenic Cadastre and the E9 declaration.
  • A neighbour’s complaint.

A Cadastre entry or E9 declaration does not, by itself, establish that an alteration complies with planning law.

The simple fact is that most of the cases we hear about began with someone saying, “I never knew the balcony wasn’t on the plans.” The owner is abroad and has no idea what the plans for their property look like, let alone whether the building has been extended or not. It’s only when someone wants to sell the property, or a repair is needed and someone is asked to sign off on the work, that the owner finds out. It’s a problem that is only discovered at the worst time possible, and with the most serious consequences.

Yanis, Founder of Home Watch Athens

Can an unauthorised construction be regularised?

It depends on the alteration’s date, category, location and eligibility. Not every unauthorised construction can be regularised.

The framework originally set out in Article 96 of Law 4495/2017 classifies unauthorised construction and changes of use into five categories:

  • Category 1: Eligible alterations completed before 9 June 1975 in buildings whose predominant use is residential.
  • Category 2: Eligible construction completed before 1 January 1983.
  • Category 3: The specific minor violations listed in the legislation.
  • Category 4: Violations meeting the statutory limits and conditions for this category, including specified overruns of permitted building parameters.
  • Category 5: Violations that do not fall within Categories 1 to 4. TaxHeaven

Eligible Category 1 to 4 alterations can be submitted electronically by an appropriately qualified engineer, with the required documents and payments. Some categories involve a filing fee without an additional special fine.

The engineer must also check exclusions, including restrictions affecting certain protected or public areas. Classification alone does not guarantee eligibility.

Ask your engineer for the calculation of fees and fines, payment options and any applicable reductions. Paying a fine without completing the required procedure is not enough.

What are the 2026 deadlines and cut-off dates?

  • Construction-date cut-off: The ordinary regularisation route concerns the unauthorised work or change of use completed before 28 July 2011. It is not enough that the original building predates that date.
  • Categories 1 to 4: The submission deadline for eligible cases is 31 March 2028.
  • Category 5: The general submission route closed on 30 September 2020. The Category 1 to 4 extension does not reopen it. Earlier special routes had their own conditions and deadlines, including deadlines ending on 31 December 2025. Do not assume an old inheritance exception remains available in 2026. TaxHeaven
  • HTK Category I buildings: The separate deadline of 1 February 2028 concerns Electronic Building Identity obligations for that building category. It is not another unauthorised-construction submission deadline. karagilanis.gr

An extension does not remove the restrictions on transferring a property with unresolved violations. Plan to investigate and resolve the issue before a transaction is pending.

What does this mean for a sale, renovation or inheritance?

Selling or gifting

The rules originally set out in Article 82 of Law 4495/2017 prohibit transfers involving specified unresolved violations, subject to exceptions.

Start the engineer’s check early so that any required regularisation, legalisation or restoration can be identified before the transaction. TaxHeaven

Inheritance

Acceptance of an inheritance is not automatically subject to the same engineer-certification requirements as a sale or gift. Your notary should confirm the requirements for the particular act.

However, outstanding violations remain attached to the property and may surface when the heirs later sell it.

Renovation

Ask your engineer whether existing deviations need to be addressed before work begins and which approvals the proposed renovation requires.

Enclosing a balcony or extending into a terrace or attic must not be treated as automatically permissible. The engineer must check whether the work is allowed and obtain the necessary approval before it starts. See our guide to renovation permits in Greece.

Before a purchase, the engineer’s technical findings and their implications should also be reviewed with your lawyer and notary.

How does the Electronic Building Identity, or HTK, connect?

The Electronic Building Identity (Ηλεκτρονική Ταυτότητα Κτιρίου), abbreviated as HTK, is a digital technical file containing permits, plans and information about the building’s legal and technical status.

For an apartment, the relevant file may be the electronic identity of the individual divided ownership.

Regularisation records must be reflected appropriately in the technical file. For the relevant later submissions, recording the building or divided ownership identity is a condition for the regularisation’s legal effects. TaxHeaven

See our guide to Electronic Building Identity in Greece.

How does an engineer’s inspection work?

Appoint an engineer with the appropriate professional rights to assess the property and handle the required submissions. They will:

  1. Collect the building permit and approved plans.
  2. Visit and measure the property.
  3. Identify and classify deviations.
  4. Advise whether they can be regularised, legalised or otherwise addressed.

Request a written assessment of the findings and proposed next steps. An inspection report is not itself a regularisation certificate or proof that every deviation can be resolved.

If you cannot travel, a relative or representative can arrange authorised access. A power of attorney is not normally needed merely to open the door, although formal authority may be required for other actions. See our guide to power of attorney for Greek property matters.

Which records should you gather?

  • The building permit, approved drawings and revisions.
  • The purchase or inheritance deed.
  • Earlier regularisation declarations and payment receipts.
  • Cadastre extracts and E9 entries.
  • Previous engineers’ certificates.
  • Dated photographs of the current condition.
  • Invoices for past works on balconies, roofs, attics or layouts.

For a more detailed list, see our Greek property documents guide.

How Home Watch Athens can help

Home Watch Athens is a founder-led, members-only service that helps people who own homes in Athens but live abroad. We help with practical coordination rather than assessing or certifying planning compliance.

  • Through our property management service in Athens, Yanis visits your home every month and provides a report with photographs. Reports and dated visit records are available through your member account.
  • When your engineer needs access, Yanis can arrange a separately agreed attendance. Yanis is the only person holding your keys on behalf of Home Watch Athens.
  • Our renovation oversight service can help establish a written brief, obtain comparative contractor quotes where available and keep agreements, invoices and photographs together. You approve the scope, cost and changes before work proceeds. Site attendance and reporting frequency are agreed for the particular project.

Additional work is quoted separately and approved by you before commencement.

We do not manage short-term rentals.