Beach Erosion and Federal Zone: The 180 Days That Decide

The sea can advance over your land and your deed will still describe the lot you bought. That's the problem. Under the Federal Zone Regulation, land covered by the sea in a definitive and permanent manner becomes National property by that fact alone, and the former owner retains a right of preference to request a concession—not ownership. The condition requires two things together, not one, and there is a notice almost no one files.

A methodological note before proceeding: the Regulation cited here was read on September 18, 2026 in two independent formats, a PDF and an HTML, and articles 3, 14, and 18 matched in number and text between both. It is transcribed with that wording and that reading date; neither format publishes a reform note regarding that language.

Does My Deed Protect Me If the Federal Zone Advances Over My Lot?

Your deed describes a fixed polygon; the coast moves, and the law defines the beach by water, not by a map. The General Law of National Property understands maritime beaches as "the portions of land that by virtue of tides are covered and uncovered by water, from the limits of greatest ebb to the limits of greatest annual flow" (art. 7, frac. IV). It is a border that changes with the tide, not a fixed measurement.

The federal maritime terrestrial zone appears in the same article, in section V, as an enumeration of common use property: it says "The federal maritime terrestrial zone;" and nothing more. That section names it but does not define it.

The survey by which the authority fixes where that strip is located proceeds at its own pace. The Regulation orders that the federal zone "shall be surveyed and delimited considering the maximum high tide elevation observed during thirty consecutive days in a season when hurricanes, cyclones, or high-intensity winds do not occur" (art. 3). A document measured over thirty days without cyclones describes a coast that behaves differently in season. That is why the map can be correct the day it was signed and become inadequate months later.

What your deed transfers in relation to the sea and what it doesn't is covered in detail in the article about what the deed does not include from the federal zone. What matters here is this: the deed does not record the movement of the line, and it is the only document in the file that the buyer usually reads. Reviewing only the deed leaves you blind to the only thing that decides.

The 180 Days: If the Sea Takes Part of My Land, Do I Still Own It?

You cease to be the owner when two conditions are met together, not one. The Regulation defines the scenario: "A piece of land is understood to have been invaded in a definitive and permanent manner when it has remained invaded by sea water for an uninterrupted period exceeding one hundred eighty calendar days and the study conducted does not foresee its gradual withdrawal" (art. 18). The two elements always go together: the uninterrupted period exceeding 180 calendar days, and also a study that does not foresee the gradual withdrawal of water. A hurricane, a high tide, or a photograph do not start that count by themselves.

When both are met, the effect is declared by the same article: "Lands that form part of the new federal maritime terrestrial zone shall become National property by that fact alone, in accordance with applicable legislation, but their former owners shall have the right of preference to have them granted as a concession, in accordance with applicable provisions" (art. 18). "By that fact alone" means the transfer occurs by the fact itself, without any sale or expropriation. There is no provision for compensation or payment for that land.

The technical work is done by the authority. When land is invaded in a definitive and permanent manner, "the Secretary shall conduct the survey, topographic-hydrographic identification and demarcation of the new federal maritime terrestrial zone" (art. 18). A warning about that name: the Regulation refers to "the Secretary" as the Secretary of Urban Development and Ecology (art. 2, frac. II); which agency today exercises that function is something you must verify separately, because this text uses the name as the Regulation itself writes it.

From all of that, the former owner retains a right of preference within an order, not ownership or a guarantee of concession. Before buying a beachfront lot, request the current study and survey: these, not the deed, are what tell you if the land is still land.

Do I Have to Notify Anyone If Water Is Covering My Land?

Yes, and the duty is yours, not the authority's. The Regulation places it on the neighboring owner: "Owners of land adjoining or adjacent to the federal maritime terrestrial zone must give written notice to the Secretary when they become aware that due to maritime movement some lands are being covered by water" (art. 18). "Must" is an obligation, not a suggestion. It is triggered by knowledge that water is advancing, not when the authority decides to look.

There is a practical reason not to overlook it. That written notice is, furthermore, the document that later proves you had knowledge of the situation and acted. When it comes time to request a concession for the lost land, your position in line must be proven with documents: the Regulation requires accompanying "documents that prove the situations referred to in article 24" (art. 26, frac. V). The owner who did not file notice arrives at that line with less to prove their case.

Can I Build a Wall or Breakwater to Defend My Land?

Defense works carry their own notice and technical requirements. The same article indicates that "interested parties shall also notify of the execution of defense works, which must comply with the technical requirements established by the Secretary itself" (art. 18). There are, then, two separate notices: one when water begins to cover the land, another regarding the work you intend to execute, and the latter subject to the technical requirements set by the authority. Before raising any defense structure, file the notice and confirm those requirements: work without notice or technical compliance does not protect you from anything, neither from the sea nor from the authority.

From Owner to First in Line, and the Line Comes After Government Agencies

The right of preference does not put you first overall: it puts you first among private parties, and only under one condition. The order of precedence applies "when private parties with equal circumstances are interested" (art. 24, preamble). It does not always apply; it applies when interested parties concur in that situation of equality.

And that entire line comes after another. The Regulation gives priority to the public sector: federal agencies and entities or state and municipal governments "shall have preference over private parties to use, exploit, or take advantage of the federal maritime terrestrial zone" (art. 23). First the public sector; then, among private parties, the order of article 24.

Within that order, whoever lost land to the sea holds first place. Section I is for the "Former owners of lands that as a consequence of maritime movement have become part of the federal maritime terrestrial zone" (art. 24, frac. I). Do not confuse that position with that of a simple neighbor: the adjoining owner who did not lose land appears further down, in section V, as "Owners or legitimate possessors of lands adjoining the areas in question" (art. 24, frac. V). These are two different scenarios and two different positions.

What Happens to My Federal Zone Concession If the Line Moves?

If you already have a concession and want to keep it, the renewal has a window and rules. It is requested "within the year prior, but at least forty-five calendar days before expiration" (art. 30, frac. I), and it proceeds only "when the surface area is equal to that originally granted in concession" (art. 30, frac. II). That renewal applicant who complied occupies section II of the order (art. 24, frac. II).

A detail that catches many: continuing to use the area and paying fees is not the same as renewal. The Regulation is literal: "The fact that the occupant continues to use the federal property area granted in concession after its expiration and makes the corresponding fee payments shall not be understood as a renewal thereof" (art. 30). Paying on time renews nothing. Mark the renewal window on your calendar and prepare your application within it; outside that period, you lose your turn.

How Do I Know Where the Federal Line of My Property Is Today?

The current survey tells you, not the deed, and the authority is obligated to keep that survey current. The Regulation assigns it to conduct "carry out, maintain, and update the technical work necessary for the topographic survey, demarcation and marking of the federal maritime terrestrial zone" (art. 14). It is not a one-time act: it is a permanent obligation, which means there is a dated version you can request.

There are two more documentary instruments. The authority compiles "the catalog and inventory of the federal maritime terrestrial zone and of lands gained from the sea" (art. 15). And it maintains a register of occupants that includes, among other data, the name of the concessionaire, the area and location of the zone, use, approved or existing works, and the validity of the concession (art. 16). These serve to know who occupies what and until when.

When requesting a concession, the process itself requires a map tied to the federal line: "Topographic survey map referred to the delimitation of the zone or, failing that, maps of national territory in geodetic coordinates" (art. 26, frac. II). That is the document that ties your polygon to the official delimitation.

Before signing, request from the file the current survey and its date, the map referred to the delimitation, and if there is a concession involved, its record. Compare them with the deed. If they do not match, the deed does not win: the survey wins.

Declared Risk: Atlas, Authorization, and What the Law Calls a Serious Crime

There is a layer of risk that is decided before the sea advances: that of civil protection. The General Law of Civil Protection defines a risk zone as the "territorial space determined in which there is a probability that damage will occur, caused by a disruptive phenomenon" (art. 2, frac. LX). The instrument that classifies it is the risk atlas, which must establish "the different levels of hazard and risk for all phenomena that affect the different zones" (art. 86).

The same law describes a criminal scenario. It considers a serious crime "the construction, building, performance of infrastructure works, and human settlements carried out in a determined zone without conducting a risk analysis and, where applicable, defining measures for its reduction, taking into account applicable regulations and the municipal, state, and National Atlases, and lacking authorization from the corresponding authority" (art. 84). It is a compound scenario: lack of risk analysis, absence of reduction measures, and absence of authorization, all together. It does not mean that building in front of an eroding beach is, by itself, a crime.

For what is already built, the law provides for an authority decision with specific studies: in settlements already established in high-risk zones, authorities "shall determine the performance of infrastructure works necessary to mitigate risk… or, where appropriate, must formulate a plan to determine which of them should be relocated" (art. 87).

What this text does not say: whether a specific zone, municipality, or development in the Riviera Maya is or is not classified as at-risk in an atlas. No atlas was consulted. You make that inquiry with the corresponding civil protection authority before buying.

What Decides Your Case, and for Whom This Is Not Enough

This text describes a threshold and a procedure; it does not resolve a specific case. Your situation depends on the current survey, the study that does or does not foresee the gradual withdrawal of water, and the authority's decision. And there is a risk that materializes before all of that: the owner who did not file written notice arrives at the line without the document with which to prove their situation, and that position must be proven with papers.

If you are a buyer for personal use of a beachfront lot, this analysis is a map of what to request; it does not replace the survey of your property or the review by a specialist. If you are looking for a fixed rule of how many meters the strip measures or a closed answer about your land, you will not find it here: it depends on the survey in your case.

If you are a foreigner and your transaction involves a federal zone concession, there are additional conditions covered in the guide on federal zone concessions and trusts.

This information is informational in nature and does not substitute for the advice of an administrative attorney specializing in national property and federal maritime terrestrial zones.

Frequently Asked Questions

Who Pays for the New Survey?

When modification of the federal zone is authorized, the Regulation requires beneficiaries to cooperate: "the beneficiaries shall cooperate in conducting the necessary studies for the delimitation and survey of the new federal zone" (art. 20). And for the concessioned area, the concessionaire must "bear the costs of survey and marking of the concessioned area" (art. 29, frac. V). Confirm in your case who assumes each study with the survey and the authority's decision.

Does It Help if My Neighbor Filed Notice and I Didn't?

The written notice is an obligation of each adjoining or adjacent property owner (art. 18), and the position in line to request a concession is proven with your own documents (art. 26, frac. V). That your neighbor filed notice proves their situation, not yours. If water is covering your land, file your own written notice; that document is part of what later proves your situation.

Does the Pool and Palapa of the Condo Fall Within the Federal Zone if the Line Moves?

What falls within the new federal zone is determined by the survey, topographic-hydrographic identification, and marking conducted by the authority (art. 18), not by eyeball estimation. Without that survey, one cannot affirm that a specific amenity is included. Request the topographic survey map referred to the delimitation (art. 26, frac. II) and its date, and check the location of each structure against it.

Does This Apply the Same If the Land Is the Condo's and Not Mine?

The duty to notify falls on owners of land adjoining or adjacent to the federal maritime terrestrial zone (art. 18), and the Regulation does not establish a different regime for the condominium, assembly, or administrator versus the adjoining owner. In condominium property, define internally who files the notice and retains the proof; the obligation to notify when water covers land does not disappear because of the property regime.