Regularising an Existing Building: Chile's Ley del Mono in 2026

An extension built "just to get by", a house put up without a permit, an enclosed barbecue area that never made it onto the drawings. It is more common than it looks, and the problem always surfaces at the same moment: when it is time to sell, to mortgage or to arrange insurance.

Reference information. Deadlines and requirements are administered by each Municipal Works Department and the rules have been extended several times; confirm both the current status and your own case before starting.

What it means for a building to be irregular

A building without a permit and without municipal approval does not exist as far as the State is concerned. The house is there, you live in it, but legally the property is recorded with less built area — or none at all. The consequences are concrete:

The bank does not count that floor area in the valuation, and often will not lend against it.
Selling gets complicated: an informed buyer discounts it from the price or walks away.
Insurers can dispute cover over anything undeclared.
The municipality can issue fines and, in extreme cases, order demolition.

The Ley del Mono: what it is and how long it lasts

Law 20.898 — known as the "Ley del Mono" — is a simplified procedure that allows you to obtain the building permit and the final approval of what is already built at the same time. That "at the same time" is the whole point: outside this mechanism they are two separate and considerably longer procedures.

It has been extended several times. The most recent extension, through Law 21.725 of March 2025, runs it to 31 December 2027.

There is also a bill currently before Congress — that is, not yet law — proposing to push the deadline towards the end of the decade and to widen the floor-area and assessed-value thresholds that apply today. Worth following, but not worth planning around: what exists today is a window closing at the end of 2027.

The thresholds are the first thing to check

The procedure does not cover every building. It is designed for homes within certain limits of floor area and assessed value, and those thresholds are precisely what the pending bill wants to widen. Before spending on a survey, ask the Municipal Works Department to confirm whether your case qualifies.

Anything falling outside the law is not left without a solution: it is regularised the normal way, with a building permit and final approval like any new build. Longer and more expensive, but it is a route.

What the procedure requires

Current title certificate.
A survey of what exists: architectural drawings of what is actually built, not of what was once intended.
A report from a qualified professional on the construction.
Certificates for the relevant installations.
Payment of municipal fees.

The survey is the part most people underestimate: what exists has to be measured and drawn, and when the work was done without a design, there is no document to start from.

Why moving early makes sense

Previous extensions produced a familiar pattern: demand piles up towards the end of the deadline and Works Departments get saturated. Filing with two years of margin is not the same as filing in the last quarter of 2027.

There is a second, less obvious reason: regularising changes the value of the property. A house with its full floor area recognised is worth more and can be financed. If you are looking at the property as a second home or a rental, this is part of the asset.

Regularising is not the same as approving a new build

If you are about to build, this does not apply to you: the right path is to do it with a permit from the start and close with the final municipal approval, which puts the house in order from day one. The full route is in the guide to municipal permits.

It is worth saying plainly: building without a permit and regularising later almost always costs more than doing it properly from the outset. It is one of the most common mistakes when building in Chile.

Have a building to regularise, or want to start off correctly? Our architecture services team handles the design and the permits. You can also write to us and we will review it.

Regularising an Existing Building: Chile's Ley del Mono in 2026