Koh Samui building permits: checking an existing property
The useful question is not simply whether the seller has a permit. It is whether the permit and its supporting file relate to the building you are buying, on the correct land, for the intended use. That requires a document comparison and, where necessary, an inspection and authority response.
Request the complete approval file
Ask for the permit, approved site plan and drawings, relevant specifications, amendments and available completion or use-related records applicable to that building. Record the permit number, authority, applicant, land references and approved use. If only a cover page is supplied, identify the missing attachments before concluding that the construction is covered. A contractor's drawing or sales floor plan should not be relabelled as an authority-approved drawing without evidence.
Compare the file to the actual building
Have an architect or engineer compare the approved arrangement with the villa's present footprint, storeys, roof, pool, terraces and retaining structures. Include the relationship to boundaries, access and site drainage. The aim is to identify discrepancies that need technical or official explanation, not to certify compliance from photographs. Where an extension was added after the initial build, request its relevant approval history rather than assuming it is covered by the original permit.
Examine dates and changes in the applicable rules
Samui's environmental framework includes a 2025 notification replacing earlier instruments. An existing building's legal position cannot be resolved by applying a current online summary backwards or assuming every older permit exempts every later change. Ask the local authority and counsel to examine the approval date, any later alteration and relevant transitional provisions. Keep the question precise: what status applies to this building and this proposed work on this parcel?
Check the use you intend after the purchase
Tell the reviewer whether the villa will remain a private residence, be significantly altered or become part of a rental business. Permission to construct a building does not by itself answer every operating or change-of-use question. Where environmental assessment requirements apply, request the relevant decision, approved scope and conditions. Match the legal project identity to the actual property; a report for a neighbouring development is not a substitute for the correct file.
Resolve missing records before assuming regularization
If the seller cannot supply a document, ask whether an authorized copy or status response can be obtained from the competent authority. Distinguish an unavailable copy from a confirmed absence of approval; they are different findings. If discrepancies remain, obtain legal advice on purchase conditions and potential consequences rather than relying on a promise that everything can be regularized later. Any technical opinion should state its inspected areas, assumptions and limitations.
- Track each discrepancy to a drawing, site observation and responsible reviewer.
- Request a written authority response where status affects the decision.
- Keep structural condition and legal approval as separate conclusions.
Verify before you pay
Tell us about the property and your proposed purchase. The client intake helps establish the checks and service scope needed. Firm availability and timing must be confirmed for your matter.
Check My Property →Questions & answers
Does a house registration book replace a permit?
No. Treat house registration, utility records and construction approvals as different records serving different purposes. Obtain the relevant permit file and compare it with the actual building.
Can every unapproved extension be legalized later?
Do not assume so. Feasibility depends on the actual works, applicable rules and authority decision. Have counsel and a qualified technical professional assess the issue before accepting that promise in a purchase.
Sources & verification limits
Use these sources to trace the rules and services discussed. Translations and summaries help with reading; they do not replace the applicable Thai text or verification for the particular parcel.
- Department of Public Works and Town & Country Planning
Official planning and building service entrypoint. Obtain current local instruments and a parcel-specific response; an older online map may not identify all operative requirements.
- ONEP — Samui / Phangan environmental protection notification B.E. 2568
Official Gazette text, 21 May 2025, replacing the 2014 instrument and 2023 extension. Read the operative provisions, maps and any amendments with the competent authority; this guide does not certify a parcel's compliance.
- ONEP — Smart EIA Plus environmental records
Project-level environmental records can support review where assessment applies. Listing alone does not prove current compliance or building approval.