Uk nhs number validate

uk-nhs-number-validate · version 1.0.0 · Identifiers & check digits · free, no key needed

Validate a 10-digit NHS number's modulus 11 check digit (NHS Data Dictionary); 11 minus remainder = 10 is never valid.

Use when you need to: validate an nhs number · check digit for a uk nhs number · is this nhs number valid.

Decide before calling

Read the versioned contract and the supported scope below. Reuse uk-nhs-number-validate@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use uk-nhs-number-validate@1.0.0 for validate an nhs number. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• validate an nhs number
• check digit for a uk nhs number
• is this nhs number valid
• verify a patient's nhs number modulus 11
• nhs number checksum check
• בדיקת מספר NHS בריטי

Not supported

• a live Personal Demographics Service (PDS) lookup
• validating a Community Health Index (CHI) or Health and Care Number (H&C number), the Scottish/Welsh schemes
• stripping hyphens or other separators (only U+0020 spaces are removed)

Behavior

• normalized = nhs_number with every U+0020 SPACE removed (the conventional 3-3-4 grouping); no other characters are stripped. normalized.length != 10 returns reason wrong_length; length 10 but not all-digit returns reason invalid_character; both leave normalized/check_digit null.
• check_digit = normalized[9], populated once length and charset pass.
• Weighted sum over the first 9 digits: weight = [10, 9, 8, 7, 6, 5, 4, 3, 2]. remainder = sum mod 11; total = 11 - remainder.
• If total == 11, expected check digit is 0. If total == 10, the number can never be valid: reason check_digit_invalid, regardless of the actual tenth digit (distinct from an ordinary mismatch, per the NHS Data Dictionary's own rule). Otherwise expected is total, compared to check_digit for reason check_digit_mismatch.

Input

• nhs_number (string, required): min length 1; max length 24

Output

• valid (boolean, required)
• reason (one of null, "wrong_length", "invalid_character", "check_digit_invalid", "check_digit_mismatch", required)
• normalized (string or null, required): pattern ^[0-9]{10}$
• check_digit (string or null, required): pattern ^[0-9]$

Limits

• max nhs number bytes: 24

Example

Request input:

{
  "nhs_number": "943 476 5919"
}

Response:

{
  "result": {
    "valid": true,
    "reason": null,
    "normalized": "9434765919",
    "check_digit": "9"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "uk-nhs-number-validate",
  "version": "1.0.0",
  "input": {
    "nhs_number": "943 476 5919"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/uk-nhs-number-validate/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"nhs_number":"943 476 5919"}'

The machine-readable contract is at /v1/tools/uk-nhs-number-validate/versions/1.0.0.

CLI

node cli.mjs run uk-nhs-number-validate 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Imo number validate: Validate a 7-digit IMO ship identification number's weighted mod-10 check digit, with or without the 'IMO ' prefix.
• Isin validate: Validate a 12-character ISIN's ISO 6166 Luhn check digit and parse its country prefix, NSIN and NSIN scheme.
• Iso6346 container validate: Validate an 11-character ISO 6346 container number's mod-11 check digit and split the owner code, category and serial.
• Npi validate: Validate a 10-digit US National Provider Identifier using the Luhn formula with the constant 80840 healthcare prefix.
• Upu s10 validate: Validate a 13-char UPU S10 postal identifier's weighted mod-11 check digit, split service indicator and country.
• Checkdigit validate: Validate a full value's trailing check digit(s) against a named algorithm (Luhn, Verhoeff, Damm, ISO 7064, GS1, mod 10).