What Is an IBAN?

IBAN stands for International Bank Account Number, a standardized format for identifying bank accounts across borders. SWIFT maintains the system under ISO 13616 and publishes a registry of every country's IBAN format^[8]. More than 80 countries use it.

Every IBAN starts with a two-letter country code, followed by two check digits, then a country-specific sequence called the BBAN (Basic Bank Account Number). The check digits let any bank or payment system verify the number before processing a transfer. IBAN became mandatory for euro credit transfers and direct debits under SEPA Regulation EU 260/2012, which took full effect in February 2014 for eurozone countries^[7].

What Does a Polish IBAN Look Like?

A Polish IBAN contains exactly 28 characters^[6][8]:

PL + 2 check digits + 8-digit bank sort code + 16-digit account number

The country code is always PL. The MOD 97 algorithm, defined in ISO 7064, produces the two check digits^[8]. The remaining 24 digits form the BBAN: an 8-digit bank sort code (numer rozliczeniowy) and a 16-digit client account number.

Here is an example:

PL 61 1090 1014 0000 0001 3210 0010

In this example, 61 is the check digit pair, 10901014 is the bank sort code, and 0000000132100010 is the client account number.

Without the PL prefix, a Polish bank account number has 26 digits. Adding PL to the front converts it to the full IBAN format^[6]. Most Polish banks display both formats in their apps and on statements.

How the Checker Validates an IBAN

The tool validates a Polish bank account number in three steps.

Step 1: Length and format. A valid Polish IBAN must be exactly 28 characters starting with PL, or 26 digits without the prefix. Any deviation fails immediately.

Step 2: MOD 97 checksum. The validator moves the first four characters to the end of the string, converts letters to their numeric equivalents, and divides the resulting integer by 97^[8]. If the remainder equals 1, the checksum passes. Any other result means the number contains an error: a mistyped digit, a transposed pair, or a fabricated sequence.

Step 3: Bank sort code lookup. The tool checks the 8-digit bank sort code against the NBP clearing directory^[3]. Every active bank and credit union in Poland has at least one registered sort code. If the code does not appear in the directory, the account number may be outdated or incorrect.

When validation fails, the checker tells you exactly what went wrong: incorrect length, failed checksum, or unrecognized sort code.

Identify Which Bank an IBAN Belongs To

The first eight digits after the check digits identify the bank. NBP assigns this 8-digit sort code and records it in the EWIB 2.0 directory^[2][3].

Paste any Polish account number into the checker to see the bank name. This is useful when you receive an account number on an invoice or by email and want to confirm it belongs to the bank the sender claims.

No tool can reveal the account holder from the number alone. An IBAN identifies the bank and branch, not the person. To verify account ownership for business or tax purposes, use the Ministry of Finance's biała lista tool (see below).

The Bank Sort Code Structure

The 8-digit sort code sits at positions 3 through 10 of the 26-digit account number, or positions 5 through 12 of the full IBAN. The NBP regulation on bank numbering defines its structure^[2]:

• Digits 1 to 3: institution number assigned to the bank
• Digit 4: internal organizational code
• Digits 5 to 7: branch or unit identifier
• Digit 8: check digit calculated with modulo 10 and weights 3, 9, 7, 1

NBP maintains the full directory of active sort codes through the EWIB 2.0 system at ewib.nbp.pl^[3]. Banks and credit unions receive new sort codes when they open branches or restructure. NBP retires old sort codes when banks merge.

The legal basis for this numbering system is Article 68 of the Polish Banking Law, which delegates sort code and account numbering rules to the President of NBP^[1].

The sort code itself contains a check digit in its eighth position, calculated using the modulo 10 formula with weights 3, 9, 7, 1^[2][5]. The IBAN checker validates this automatically.

NRB: The Polish Account Number Standard

Before IBAN became widespread, Poland used its own 26-digit format called NRB (Numer Rachunku Bankowego). Polish Standard PN-F-01102 defines the NRB format, and the NBP regulation references it directly^[2].

In practice, the NRB and the BBAN portion of a Polish IBAN are the same 26-digit number. The difference is purely presentational: NRB is the domestic format, and IBAN adds the PL prefix plus two check digits for international compatibility^[5][6].

Polish banks accept both formats for domestic transfers. SEPA requires the full IBAN format for international transfers^[7].

IBAN, BIC, and SWIFT Codes

An IBAN identifies a specific bank account. A BIC (Bank Identifier Code), also called a SWIFT code, identifies the bank itself^[6]. A BIC is 8 or 11 characters long.

For international transfers, you typically need both the recipient's IBAN and the bank's BIC/SWIFT code. SEPA dropped the BIC requirement in February 2016 for euro payments, so the IBAN alone is enough within the eurozone^[7]. For transfers in Polish złoty from outside the EU, or for non-SEPA currencies, you still need the BIC.

Your bank's BIC/SWIFT code is on their website, in your banking app, or on your account statement.

When to Check an IBAN

Verify an IBAN before any first-time transfer. This matters most when you received the number by email, SMS, or messaging app, where digits can be mistyped or tampered with.

Paying a Polish invoice: copy the account number from the invoice into the checker to confirm the format and bank before entering it in your banking app.

Setting up a new payee: if a landlord, employer, or business partner sends you their account number, run it through the checker to confirm the digits are valid and the bank matches expectations.

Receiving an unexpected payment request: if someone sends you an account number you have not seen before, checking it takes seconds and can flag obvious problems.

The checker validates format, checksum, and bank sort code. It does not confirm account ownership or check whether the account is active.

IBAN and the Biała Lista (VAT Whitelist)

If you run a business in Poland, you may need to verify that a supplier's bank account appears on the biała lista (VAT taxpayer whitelist). Since January 2020, businesses cannot deduct payments over 15,000 PLN made to accounts not listed on the biała lista^[9].

The biała lista is a separate system maintained by the Head of KAS (Krajowa Administracja Skarbowa)^[9]. This IBAN checker validates technical correctness: format, checksum, and bank sort code. The biała lista verifies tax registration. For VAT whitelist checks, use the official search tool at podatki.gov.pl^[9].

Common Questions

Can someone withdraw money from my account if they know my IBAN?

No. An IBAN identifies your account for incoming transfers. It does not grant anyone access to withdraw funds. You share your IBAN every time someone pays you. Giving it out is no riskier than giving out an email address.

Why does my bank show 26 digits but the invoice says 28 characters?

The 26-digit version is the domestic NRB format. The 28-character version adds the PL country prefix. They represent the same account. Polish banks accept both for domestic transfers.

Does this tool work for non-Polish IBANs?

No. This checker validates Polish IBANs only. It checks sort codes against the NBP directory, which covers Polish banks and credit unions exclusively.

Can I use the IBAN checker to verify a biała lista registration?

No. The IBAN checker validates the number's format and identifies the bank. Biała lista registration is a separate tax system. Use the official tool at podatki.gov.pl for VAT whitelist lookups^[9].

References

1. Banking Law (Prawo bankowe) — Art. 68, Consolidated Text, Dz.U. 2024 poz. 1646 — isap.sejm.gov.pl
2. NBP President's Regulation on Bank and Account Numbering (Zarządzenie nr 7/2017), Consolidated Text, Dz. Urz. NBP 2025 poz. 29 — dzu.nbp.pl
3. EWIB 2.0 — NBP Online Directory of Financial Institutions — ewib.nbp.pl
5. NBP Analytical Report: Bank and Account Numbering — History and Current State (June 2014) — nbp.pl
6. European Consumer Centre Poland — What is IBAN and BIC/SWIFT? — konsument.gov.pl
7. EU Regulation 260/2012 (SEPA Regulation) — eur-lex.europa.eu
8. SWIFT — IBAN Registry (ISO 13616) — swift.com
9. VAT Taxpayer Register (Biała Lista) — Biznes.gov.pl Guide — biznes.gov.pl