NRB

NRB (Numer Rachunku Bankowego) is the Polish domestic bank account number format. It consists of 26 digits: a 2-digit MOD-97 check, an 8-digit bank sort code, and a 16-digit account number. The international IBAN form is PL followed by the 26-digit NRB.

Usage

use SlashLab\Numerik\Numerik;

// Boolean
Numerik::nrb()->isValid('61102010260000000000000000');   // true

// Spaced format is accepted and normalised
Numerik::nrb()->isValid('61 1020 1026 0000 0000 0000 0000');   // true

// IBAN format (PL prefix) is accepted and stripped during normalisation
Numerik::nrb()->isValid('PL61102010260000000000000000');        // true
Numerik::nrb()->isValid('PL61 1020 1026 0000 0000 0000 0000'); // true

// Rich result
$result = Numerik::nrb()->validate('61102010260000000000000000');
$result->isValid;   // true

// Parse to value object
$nrb = Numerik::nrb()->parse('61102010260000000000000000');

// Null on failure instead of exception
$nrb = Numerik::nrb()->tryParse('bad-input'); // null

Value object API

parse() and tryParse() return a SlashLab\Numerik\ValueObjects\Nrb instance.

Core

Method	Return type	Description
getRaw()	string	The original input, untouched.
getNormalized()	string	26 digits, no prefix, no spaces.
__toString()	string	Same as getNormalized().

Formatting

Method	Return type	Description
getFormatted()	string	Standard Polish display format: CC BBBB BBBB AAAA AAAA AAAA AAAA.
getIban()	string	Full IBAN string: PL + 26 digits, e.g. PL61102010260000000000000000.
getFormattedIban()	string	Grouped IBAN: PL61 1020 1026 0000 0000 0000 0000.

Structure

Method	Return type	Description
getCheckDigits()	string	First 2 digits — the MOD-97 check value.
getSortCode()	string	8-digit bank sort code (bank identifier + branch + internal check).
getBankCode()	string	First 3 digits of the sort code — identifies the bank.
getAccountNumber()	string	Last 16 digits — the customer account number.

Examples

$nrb = Numerik::nrb()->parse('61102010260000000000000000');

$nrb->getRaw();             // '61102010260000000000000000'
$nrb->getNormalized();      // '61102010260000000000000000'
$nrb->getFormatted();       // '61 1020 1026 0000 0000 0000 0000'
$nrb->getIban();            // 'PL61102010260000000000000000'
$nrb->getFormattedIban();   // 'PL61 1020 1026 0000 0000 0000 0000'
$nrb->getCheckDigits();     // '61'
$nrb->getSortCode();        // '10201026'
$nrb->getBankCode();        // '102'
$nrb->getAccountNumber();   // '0000000000000000'

// Input formats are all equivalent
$a = Numerik::nrb()->parse('61102010260000000000000000');
$b = Numerik::nrb()->parse('61 1020 1026 0000 0000 0000 0000');
$c = Numerik::nrb()->parse('PL61102010260000000000000000');

$a->getNormalized() === $b->getNormalized(); // true
$b->getNormalized() === $c->getNormalized(); // true

Validation algorithm

NRB uses the standard IBAN MOD-97 checksum:

1. Strip spaces and hyphens. Strip the optional PL country prefix. Reject inputs over 40 characters.
2. Assert exactly 26 digits remain; fail with InvalidLength.
3. Assert all characters are digits; fail with InvalidCharacters.
4. Verify the MOD-97 checksum:
   • Rearrange as: digits 3–26 (the BBAN) + 2521 (numeric encoding of PL) + digits 1–2 (check digits).
   • Compute the resulting number modulo 97.
   • Fail with InvalidChecksum if the result is not 1.

Failure reasons

Reason	Value	When
InvalidLength	invalid_length	Input is not exactly 26 digits after normalisation, or exceeds 40 characters raw.
InvalidCharacters	invalid_characters	Non-digit characters remain after stripping whitespace, hyphens, and the PL prefix.
InvalidChecksum	invalid_checksum	MOD-97 remainder is not 1.