Validate a Canadian SIN (NAS)

VerifNow validates a Canadian Social Insurance Number — numéro d’assurance sociale, hence the endpoint name nas — for its format and its Luhn check digit, and reports what the number’s series says about it.

Only collect a SIN where the law requires it. In the private sector that essentially means employers, for income reporting, and financial institutions, for interest-bearing and registered accounts. The federal government’s guidance to individuals says it plainly: some businesses may ask for your SIN, and “this is strongly discouraged, but not illegal”. Validating a SIN you should not be holding does not make holding it better.

Basic SIN validation


POST https://api.verifnow.io/api/v1/validate/nas
X-API-KEY: your_api_key_here
Content-Type: application/json
 
{
  "value": "046 454 286"
}

Example response


{
  "valid": true,
  "message": "Valid SIN format, but numbers starting with 0 are not issued to individuals",
  "normalizedValue": "046454286",
  "originalValue": "046 454 286",
  "validationLevel": "STANDARD",
  "nasDetails": {
    "checksum_valid": true,
    "temporary_resident": false,
    "individual_series": false,
    "formatted": "046 454 286"
  }
}

046 454 286 is the sample number the Government of Canada prints on example cards. It is well formed and its check digit is correct — and it starts with 0, a series not issued to individuals, which is exactly why it is safe to use as an example. See below.

Spaces and dashes are accepted. normalizedValue is the nine digits; formatted is the printed form, in three groups of three.

`nasDetails`

Field	Meaning
`checksum_valid`	The Luhn check digit is correct.
`temporary_resident`	The number starts with 9. SINs issued to temporary residents always do, and they expire with the holder’s work permit, study permit or visitor record.
`individual_series`	The first digit belongs to a series issued to individuals: 1 to 7, or 9. `false` for numbers starting with 0 or 8.
`formatted`	`046 454 286`.

valid means well formed with a correct check digit. The two series flags are reported, not enforced — valid stays true — so that you decide what they mean for your use case.

Why the series are flags, not rejections

Numbers starting with 0 are used for tax numbers the Canada Revenue Agency assigns to people who cannot get a SIN, and numbers starting with 8 for business numbers. Service Canada does not publish its allocation table, so this rests on consistent secondary sources rather than an official list — reason enough to report it rather than refuse on it. For payroll, you will want to reject both; see the article for the reasoning.

What the number cannot tell you

When a temporary resident’s SIN expires. The date is on the holder’s immigration document, not in the number. temporary_resident: true is your cue to ask for it.
The province. The first digit once identified the province of registration, but numbers have been issued across series when a region ran short. A province read from the digit would be a guess, so the API does not return one.
Whether the SIN was issued, or to whom. Only Service Canada knows. An employer relies on the SIN confirmation letter the employee receives.

Common responses

Input	`valid`	`message`
`046 454 286`	`true`	Valid SIN format, but numbers starting with 0 are not issued to individuals
A 1-to-7 series number with a correct check digit	`true`	Valid SIN
A 9-series number with a correct check digit	`true`	Valid SIN — temporary resident: it expires with the holder’s permit
`046 454 287`	`false`	SIN check digit does not match — please check the number
`04645428`	`false`	A SIN is exactly 9 digits
`000 000 000`	`true`	Valid SIN format, but numbers starting with 0 are not issued to individuals

000 000 000 passes the Luhn check — its digit sum is zero — which is why a checksum-only validator accepts it. The series flag is what catches it.

Test with the sample number

Use 046 454 286 in tests, fixtures and documentation. Do not invent a “valid” SIN from the 1-to-7 or 9 series: roughly one nine-digit number in ten has a correct check digit, and tens of millions of SINs have been issued, so a made-up valid number stands a real chance of being someone’s actual SIN. If a test needs one, compute it at run time from a prefix rather than committing it as a literal.

What VerifNow keeps

The usage log that meters your calls stores a SIN as *** — no digits at all. See Rate Limits for quotas; validation of a SIN counts as one call on every plan.

Next steps

Validating a Canadian SIN — what to accept, what to reject, what to store
Error Handling — status codes and transport failures