Filling out an online address form should be simple. Locality, street, address complement: three fields that appear on almost all administrative or delivery forms. Yet, confusion between these fields is enough to cause returned mail or a lost package. This article compares the exact function of each field, the data it expects, and the most common input errors.
Comparison Table: Locality, Street, and Address Complement
Before diving into the details, a table clarifies what each field designates, what it contains, and where it is placed on the envelope or in a postal data flow.
| Field | Definition | Expected Content | Position on the Envelope | Required? |
|---|---|---|---|---|
| Street | Line that carries the number, type, and name of the street | 12 rue de la République, 8 avenue du Général Leclerc | Central line of the address | Yes |
| Address Complement | Element located outside or inside the building to specify the location | Building C, Residence Les Lilas, Entrance 3, Staircase B | Intermediate line (above or below the street according to the standard) | No |
| Locality | Last line of the address, identifying the destination municipality | Postal code + name of the municipality (75019 Paris, 22000 Saint-Brieuc) | Last line | Yes |
This structure corresponds to the main triplet used by the Local Address Base (BAL): number + street name + municipality. The complement remains an optional field in most systems, which explains why it is often hidden or minimized on online forms.
Knowing how to differentiate locality, street, and address complement prevents placing a residence name in the street field or a postal code in the complement, two errors that disrupt the automated processing of mail.
Street Field: Number, Type, and Name on a Single Line
The street field concentrates three inseparable pieces of information. The street number comes first, followed by the type of street (street, avenue, boulevard, dead end, path) and then the proper name of the street.
In the address “10 boulevard Haussmann,” the street designation is “boulevard Haussmann” and the number is “10.” Some forms separate the number from the designation, while others group them into a single field.
The common point remains that the place name is not a street designation in the strict sense. The BAL classifies the place name outside the main triplet; it should therefore not be entered in the street field but in the complement, when the form allows it.
Case of New Street Names
Municipalities can rename a street following a municipal deliberation. These changes are subject to institutional monitoring, and forms must incorporate a logic of continuous updating of designations. An outdated designation in the street field can lead to rejection during automated postal processing.
Address Complement: What Specifies Without Replacing the Street
The address complement serves to locate the recipient within a larger set than just the street. In the API Enterprise and IGN flows, this field is defined as an element located outside the building to complete the address, with examples such as residence, building, entrance.
On the other hand, internal information about the housing unit (floor, door, staircase) also falls under the complement but on a separate line in the postal standard. Online forms often merge these two levels into a single free text field.
Here are the elements that belong to the complement and not to the street:
- Residence, subdivision, or real estate complex (e.g., Residence Les Acacias)
- Building, tower, or entrance (e.g., Building D, Entrance 2)
- Floor, staircase, door, or mailbox (e.g., 3rd floor left)
- Place name, when no street number exists in the municipality
The complement never replaces the street. A form that does not display a complement field expects these details to be added at the end of the street line, after a comma. Omitting the complement in a collective building risks mail being delivered to the wrong recipient.
Locality and Postal Code: Last Line, Decisive Role for Sorting
The locality appears on the last line of the address. It combines the postal code and the name of the municipality. It is this line that determines the sorting center to which the mail is directed. An error in the postal code redirects the shipment to another municipality, even if the street and complement are correct.
Locality and Place Name: Two Distinct Concepts
A place name is not a locality in postal terms. The locality remains the administrative municipality. When a recipient lives at the place name “Le Bois Joli” in the municipality of Plaintel, the locality field must contain “22940 Plaintel,” and the place name should appear in the complement or in the street if no other address exists.
Confusing place names and locality leads to frequent errors on forms where the “city” field is free. The postal system expects the official name of the municipality, not that of the hamlet.
Common Input Errors and Their Impact on Postal Processing
Errors in distributing data between these three fields are not trivial. The automated processing of mail relies on the position of data in each line.
- Entering the name of the residence in the street field instead of the complement: the machine does not recognize the designation, and the mail goes into manual processing
- Placing the place name in the locality field instead of the official municipality: the postal code no longer matches, and the shipment is redirected or returned
- Omitting the address complement in a collective building: the mail carrier has to guess the floor or building, which delays delivery
- Using an old street designation after a name change: automatic rejection occurs as soon as it reaches the sorting center
On online forms, the quality of addressing also depends on the length allowed by each field. Some forms limit the number of characters in the complement, forcing abbreviations. Standardized postal abbreviations (Bt for building, Esc for staircase) remain the best option to avoid truncating information.
The distinction between locality, street, and complement is based on a simple principle: the street locates the building, the complement locates the recipient within the building, and the locality identifies the municipality. Keeping this triptych in mind when filling out a form is enough to avoid the vast majority of addressing errors.