Buying a house in Baja California with unpermitted construction

By Lic. Pati Claudia Galarza, attorney (Licenciada en Derecho), Cédula Profesional 15176510 · Published October 18, 2026 · Español

Yes, you can buy a house whose construction has no permit or was never declared, but find out exactly what is missing before you sign, because the problem stays with the property and becomes yours. Under the laws of Baja California, it is the owner who must regularize the construction, pay any fines and update the catastral record. The best time to fix it, or to build its cost into the price, is before the escritura is signed, and usually at the seller's expense.

What the escritura and the catastral record show

The escritura describes the property. The notary must identify it so it cannot be confused with another, stating its nature, location, boundaries and, where possible, its surface area (Ley del Notariado para el Estado de Baja California, art. 121). Many older deeds describe only the land, or a house much smaller than what stands there today.

The municipal catastro keeps its own record of land area, built area and their characteristics, which produce the valor catastral used for predial. Owners must report new construction, additions and remodels to the catastral authority within 15 business days (Ley del Catastro Inmobiliario del Estado de Baja California, art. 37), and the valor catastral is updated when construction notably changes the value (art. 28). If an owner never reported an addition, the catastral record shows less than what is built.

Compare three things: the built area in the escritura, the built area in the catastral record (the predial statement or a catastral certificate), and what you see on site. If they do not match, that is the issue this article is about.

Why the notary and the tax office care

Before an escritura that transfers ownership, the notary needs an acta de trabajo topográfico certified by the catastral authority and no more than one year old (Ley del Catastro, art. 38). If the dimensions differ from the title, catastro orders a deslinde at the owner's cost (art. 43).
The notary may not sign off on the transfer without proof that the ISAI is paid, that the property's municipal taxes are current and that the deslinde was done (Ley de Hacienda Municipal del Estado de Baja California, art. 75 Bis B, section A, fr. IX).
The ISAI base is the highest of the updated price, the valor catastral and the commercial value in an avalúo by an authorized appraiser (art. 75 Bis B, fr. II). The avalúo must describe the construction and include photographs (section B), so the tax can reflect what is actually built, not only what catastro shows. An avalúo loses effect if construction is done after it was made.

If you are borrowing, or buying through a fideicomiso, ask the lender or the bank trustee early what it requires about permits and built area.

Construction licences and occupancy under state law

The Ley de Edificaciones del Estado de Baja California requires a licencia de construcción from the municipality before anyone builds, enlarges, modifies, repairs, remodels or demolishes, or changes the use of a building (art. 58). Minor work, such as interior painting or floor repairs that do not touch the structure, is listed as work the municipal reglamentos may exempt (art. 59).

When the work is finished, the owner and the responsible construction director must give written notice of completion (aviso de terminación de obra) and request the occupancy authorization. The municipality grants it after inspecting that the building matches the approved project (art. 65).

Building without a licence can be fined up to 8% of the value of the property (art. 73, section A, fr. III). Not giving the completion notice on time carries a fine of 5 to 250 UMA (art. 73, section A, fr. I). The authority can also order partial or total demolition of work that does not meet the reglamentos (art. 73).

Estimate as of 2026: 5 to 250 UMA is roughly MXN 587 to MXN 29,328, using the 2026 daily UMA of MXN 117.31 (published in the DOF on 9 January 2026, in force from 1 February 2026). Peso figures are approximate, and the authority sets each fine within the legal range.

Regularizing the construction

Work built totally or partly without a licence can be regularized. The owner must at least pay the fines imposed, obtain a licencia de regularización, make any changes the municipality orders, and meet whatever else the municipal reglamento requires (Ley de Edificaciones, art. 64). The owner then reports the construction to catastro so the record and the valor catastral are updated (Ley del Catastro, art. 37).

Each municipality sets its fees in its annual Ley de Ingresos. For 2026, Playas de Rosarito (art. 27, fr. C), Tijuana (art. 31, fr. III) and Ensenada (art. 28) charge regularization at 50% on top of the normal construction licence fee. San Felipe charges houses over 60 m2 that were started without a licence an extra 50% of the licence cost (art. 38).

Estimate as of 2026: the 50% is added to the normal licence fee, which is charged per square metre. Fines, plans by an architect or engineer, any required changes and the catastral update are separate costs. Ask the municipality to estimate the actual file before you agree on a price.

How it affects the price and the purchase contract

Treat missing permits as a cost and a risk. Get an estimate of what regularization will take, and decide who does it and when. Common options:

The seller regularizes before closing, and your escritura describes the house as it really is.
The price is reduced by the estimated cost, and you regularize after closing.
Part of the price is paid only when the seller delivers the licence, the terminación de obra or the updated catastral record. Galarza Legal never receives or holds any part of the price; payments go as the contract provides.

Put it in writing in the promesa de compraventa: a description of the construction as it is, who pays regularization, fines and fees, a deadline, and what happens if the municipality refuses the licence or orders changes or demolition.

Do not count on a claim after closing. The Código Civil para el Estado de Baja California makes the seller answer for hidden defects, for two years from delivery in the case of real property (arts. 2017 to 2024), but not for defects that are evident (art. 2018). A problem you knew about before signing is hard to present as hidden, so your protection is what the contract says.

The construction in your escritura

Ask the notary early how the construction will appear in your deed. If the seller's escritura describes only land or a smaller house, the notary can tell you which documents are needed to declare the existing construction, for example the licence, the terminación de obra, the updated catastral record and the avalúo, and whether this can be done in the same escritura or needs a separate instrument. Do this before you set the closing date.

Buyer checklist

Get the seller's escritura and compare its description with the house.
Get the catastral record and the latest predial statement, and compare the built area.
Ask for the construction licences, plans, aviso de terminación de obra and occupancy authorization for every part of the house, including additions, roof decks, pools and casitas.
Confirm the lot comes from an approved subdivision: no construction licence is granted on lots split without approval until they are regularized (Ley de Edificaciones, art. 58).
If something is missing, get a written estimate of regularization: fees, fines, plans and changes required.
Agree in the promesa who regularizes, who pays, by when, and what happens if it fails.
Ask the notary how the construction will be declared in your escritura and what documents they need.
Budget the ISAI on the higher value the avalúo may show, and keep the closing date realistic.

How Galarza Legal can help

We review the escritura, the catastral record and the permits, explain what is missing and what it may cost, draft or review the promesa de compraventa with the right conditions, and coordinate with the notary and the municipality. You pay the notary, the municipality and the appraiser directly.

Frequently asked questions

Can I buy a house in Baja California that has no construction licence?

Yes. Nothing in the building law stops the sale itself, but the new owner inherits the duty to regularize, the possible fines and the cost of updating the catastral record. Agree in the purchase contract who handles it and who pays.

How much is the fine for building without a licence in Baja California?

The Ley de Edificaciones allows a fine of up to 8% of the value of the property for work done without a licence (art. 73). The municipality sets the actual amount, and regularization fees are separate.

What does it cost to regularize construction in Rosarito or Tijuana?

As of 2026, both municipalities charge the normal construction licence fee per square metre plus 50% for regularization, under their 2026 Leyes de Ingresos. Fines, plans and any required changes are extra. Treat any figure as an estimate until the municipality quotes your file.

Will undeclared construction raise my ISAI?

It can. The ISAI is calculated on the highest of the price, the valor catastral and the appraised commercial value, and the avalúo describes what is actually built (Ley de Hacienda Municipal, art. 75 Bis B).

General information about Mexican law as of the date shown; not advice on a specific case. Every figure is an estimate.