National Insurance Number Format Support

We clean National Insurance numbers from many different input formats. See what we support below.

Supported Format Variations

Spacing Variations

AB 12 34 56 C

AB12 34 56 C

AB 123456 C

AB 12 3456 C

AB 1234 56 C

AB123 456 C

AB123456C

A B 12 34 56 C

Separator Types Handled

AB-12-34-56-C

AB.12.34.56.C

AB/12/34/56/C

AB_12_34_56_C

AB:12:34:56:C

AB;12;34;56;C

AB,12,34,56,C

AB|12|34|56|C

We handle dashes, dots, slashes, underscores, colons, semicolons, commas, pipes, and more.

Parentheses & Brackets

(AB)12 34 56 C

AB(12)34 56 C

AB 12 34 56(C)

(AB123456C)

[AB]12 34 56 C

{AB}12 34 56 C

AB[123456]C

AB{123456}C

Mixed Formatting

AB 12-34-56 C

AB-12 34 56-C

AB.12-34.56-C

AB 12.34.56 C

AB-123456 C

AB12-34 56-C

Labels & Prefixes Removed

NI: AB123456C

NI Number: AB123456C

NINO: AB123456C

National Insurance: AB123456C

AB123456C (NI)

NI - AB123456C

UK AB123456C

GB: AB123456C

Wrapping Characters

"AB123456C"

'AB123456C'

*AB123456C

#AB123456C

AB123456C

'AB123456C

Lowercase & Case Variations

ab123456c

ab 12 34 56 c

Ab123456C

aB123456C

AB123456c

ab123456C

Ab 12 34 56 C

aB 12 34 56 C

All NI numbers are normalized to uppercase during validation.

Output Format

All National Insurance numbers are formatted consistently as:

AB 123456 C

Two letters, six digits, one letter, with appropriate spacing.

✓ Validation Rules

• Must contain exactly 2 letters, 6 digits, and 1 letter
• Banned prefixes (BG, GB, KN, NK, NT, TN, ZZ) are rejected
• Administrative prefixes (OO, FY, NC, PZ) are rejected
• Invalid characters (D, F, I, O, Q, U, V) in specific positions are rejected
• TRN (Temporary Reference Number) format is detected and rejected
• PP999999P is specifically rejected

Have a Format We Don't Support?

If you have National Insurance number data in a format we don't currently handle, please contact us with examples and we'll add support!

Back to Validation Rules