# `UkNationalInsuranceNumber`

A UK National Insurance number: `AB123456C`.

Use it for payroll and benefits. For tax numbers from any country, use [`TaxId`](/docs/types/type-tax-id.md).

## Shape

One value, held as text in one set form, with no parts: `CE987654A`.

## Example

```jadpo
UkNationalInsuranceNumber("AB123456C")
```

`UkNationalInsuranceNumber(raw)` checks the text, and text that isn't one breaks the `format` rule.

`text.parse(raw, as: UkNationalInsuranceNumber)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `QQ123456C`, `GB123456A` or `AO123456A`.

## Good to know

- Write it with no spaces. `text.format` adds them: `AB 12 34 56 C`.
- It refuses prefixes HMRC doesn't allocate, such as `QQ`, and `GB`.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.
- A field that holds one counts as personal data (`government_id`), so you don't mark it yourself.

## In JSON

A string, in a request, a response or `json.write`:

```json
"AB123456C"
"CE987654A"
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`UkNationalInsuranceNumber` is in the group Tax and identity numbers, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `AB123456C` and `CE987654A`.

### How it is stored

It is stored in one column named for the field, of type `text`. `CE987654A` is stored as `'CE987654A'`.

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale.

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `AB123456C` | `AB 12 34 56 C` |
| `CE987654A` | `CE 98 76 54 A` |

### Operations

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>