# United Kingdom (GB)

UK addresses use an alphanumeric postal code with a significant space, place the
house number before the street name, and often include building names. The
hierarchical address system makes [autocomplete](/developer-resources/ingrid-api/guides/address-autocomplete)
particularly valuable — a single street can contain dozens of individual
premises.

## Example


```json
{
  "countryCode": "GB",
  "postalCode": "SW1A 2AA",
  "addressLines": ["10 Downing Street"],
  "locality": "London"
}
```

## Field requirements

| Field | Required | Description |
|  --- | --- | --- |
| `countryCode` | Yes | Always `"GB"` |
| `postalCode` | Yes | Alphanumeric with space |
| `addressLines` | Yes (for shipment) | Index 0: number and street name |
| `locality` | Yes (for shipment) | Post town |
| `administrativeArea` | No | County — not required for delivery |
| `subLocality` | No | London district or neighborhood, e.g., `"Westminster"` |


## Postal code

- **Format:** Alphanumeric, with a space separating the outward and inward parts
- **Pattern:** Various formats (`A9 9AA`, `A99 9AA`, `A9A 9AA`, `AA9 9AA`, `AA99 9AA`, `AA9A 9AA`)
- **Examples:** `"SW1A 2AA"`, `"EC2R 8AH"`, `"M1 1AE"`
- **Sanitization:** The API preserves spaces. Letters are uppercased.


The space in UK postal codes is significant. `"SW1A 2AA"` and `"SW1A2AA"` may
be handled differently by carriers. Always include the space.

## Address lines

The house number comes **before** the street name. Building names, when present,
go on a preceding line.

| Scenario | `addressLines` value |
|  --- | --- |
| Standard | `["10 Downing Street"]` |
| With building name | `["Buckingham Palace", "The Mall"]` |
| With flat number | `["Flat 3", "10 Buckingham Street"]` |


- Building names are common in the UK and may replace a house number entirely
- The [autocomplete endpoint](/developer-resources/ingrid-api/guides/address-autocomplete) returns building names
in the correct position


## Locality

The `locality` field is the **post town**, which may differ from the colloquial
city name.

- **Example:** `"London"`, `"Manchester"`, `"Edinburgh"`
- For London addresses, `subLocality` can capture the specific district


## Autocomplete considerations

UK addresses benefit significantly from autocomplete due to:

- **Multi-premise buildings:** A single building may contain many flats, each
a separate address. The expand/resolve pattern handles this naturally.
- **Building names:** Many UK addresses use building names instead of or in
addition to house numbers, making free-text entry error-prone.
- **PAF data:** The UK has a comprehensive Postcode Address File. The
[autocomplete endpoint](/developer-resources/ingrid-api/guides/address-autocomplete) with `focus=postalCode`
enables postcode-first lookups common in UK checkouts.


## Common mistakes

| Mistake | Problem | Fix |
|  --- | --- | --- |
| `"postalCode": "sw1a 2aa"` | Lowercase postal code | Accepted — the API uppercases automatically |
| `"postalCode": "SW1A2AA"` | Missing space | Include the space: `"SW1A 2AA"` |
| `"addressLines": ["Downing Street 10"]` | Street before number | UK uses number-first: `["10 Downing Street"]` |
| Missing building name | Building-only addresses fail delivery | Use autocomplete to capture building names |