Official Number & Alineamiento: Process, Cost and Validity

When you buy a lot or plan to build, sooner or later two documents come up that many people confuse or have never heard of: the official number (número oficial) and the alignment certificate (constancia de alineamiento). Both are issued by the municipality and, although they sound like pure red tape, they are the legal basis that defines your address and the boundary of your property along the street. In this guide we explain what they are, what they are for, when you need them and how to get them, keeping in mind that requirements and costs vary from one municipality to another in Mexico.

What is the constancia de alineamiento?

The constancia de alineamiento (alignment certificate) is a document issued by the municipal authority (usually the Urban Development or Public Works department) to define precisely the boundary between your lot and the public thoroughfare. In other words, it marks where your property ends and where the street, the sidewalk or any common-use area begins.

That boundary is not arbitrary: it ensures that buildings respect an orderly urban layout, it reserves space for sidewalks, roadways and future road widening, and it prevents a wall or a house from encroaching on the public right-of-way. The alineamiento is usually accompanied by information such as the applicable building restrictions and, in some municipalities, the official number on the same document.

What is the número oficial?

The número oficial (official number) is the identifier the municipality assigns to your lot within a street: it is, quite literally, your official address. Although it may seem like a minor detail, this number is what gives certainty about your property's location and is the one recognized by government agencies, notaries and utility companies.

It does not always match the number someone painted on the facade on their own. The official number is assigned following the order and street-numbering system the municipality uses, and it is recorded in a document (a constancia or certificate of official number) that is later used to execute the deed and to sign up for services such as water, electricity or gas.

Differences between the two documents

Although they are often processed together and in some municipalities are delivered as a single document, they serve different purposes. This table summarizes the main difference:

When do you need them?

These documents are not a mere formality: in several procedures they are indispensable. The most common scenarios are:

• When building: the alineamiento is usually a prerequisite for obtaining your permit or construction declaration (manifestación de construcción), because it defines where you can build.
• When executing the deed: the notary public (notario público) usually asks for the official number so the property's address is recorded correctly in the escritura.
• When signing up for services: water, electricity or gas companies usually require an official address to activate the supply.
• When regularizing or subdividing: any filing with Desarrollo Urbano usually relies on these documents.

If you are at the buying stage, it also pays to check the land use (uso de suelo) of the lot to confirm you can use it for what you have in mind. You can browse available options in our lots for sale section.

How to apply and required documents

The procedure is carried out with the municipal authority, normally at the Urban Development, Public Works or Catastro (property registry) office, depending on the municipality. It is increasingly common to be able to start it online, although it usually still requires a visit to submit documents or pick up the result. In broad strokes, the process goes like this:

1. Go in person to, or log into the portal of, the relevant municipal office.
2. Request the alineamiento and official number form (in many municipalities it is a single procedure).
3. Submit the required documentation and pay the fees (pago de derechos).
4. Wait for the review; in some cases an inspection of the lot is carried out.
5. Receive your certificate with the alineamiento and the assigned official number.

The documents typically requested (always verify the current list for your municipality) include:

• Deed or document proving ownership or possession of the lot.
• Official ID of the owner or the authorized representative.
• Up-to-date predial (property tax) bill.
• Location sketch or plan of the lot.
• Proof of payment of the corresponding fees.

Approximate cost and validity

The cost depends on each municipality's revenue law (ley de ingresos) and is usually calculated based on factors such as the lot's street frontage in meters or a flat fee. In general terms, it tends to be a moderate-cost procedure compared with other construction permits, but there is no single nationwide rate, so it is best to check the current figure directly with your municipality.

As for validity, the official number is normally permanent as long as the area's street-numbering system doesn't change, while the alineamiento may have a limited validity for building purposes. If your project is delayed, check whether you need to renew it before starting work.

If you are still evaluating a purchase and want an idea of the value of a lot or property, you can use our tool to calculate how much it is worth before investing in paperwork.

Frequently asked questions

Is the official number the same as the number on the facade?

Not necessarily. The official number is the one the municipality assigns and recognizes; the one painted on the house may not be formalized. Ideally, both match and correspond to the document issued by the authority.

Can I build without the constancia de alineamiento?

It is not advisable. The alineamiento is usually a requirement for obtaining the construction permit or declaration and defines how far you can build. Building without it exposes your work to fines or corrections.

Are they processed separately or together?

It depends on the municipality. In many cases the alineamiento and the official number are requested and delivered in a single procedure; in others they are separate filings. Confirm how your locality handles it.

Who can request them?

Generally, the owner of the lot or a person authorized through a power of attorney (carta poder) or legal representation. You will need to prove ownership or possession with the documentation the municipality asks for.