IBAN validator: check an account before you pay
Paste the IBAN and see at once whether it is correctly formed: country code, length, characters and check digits. For Romanian accounts you also get the bank. The IBAN stays in your browser.
- Runs locally, in your browser
- ISO 13616 · MOD 97-10
- Romania and 88 more countries
Reviewed by Silvia, Chartered Accountant (CECCAR) · updated
The tool
The result appears here: valid or invalid, with the exact reason, the country, the length and, for Romanian accounts, the bank.
Rates and rules used
- IBAN structure
- ISO 13616country code, 2 check digits, then the domestic account (BBAN)
- Check digits
- MOD 97-10ISO/IEC 7064: the remainder of the division by 97 must be 1
- Romanian IBAN
- 24characters: RO + 2 digits + 4 letters (bank) + 16 alphanumerics
- Maximum length
- 34characters; each country has one fixed length, from the SWIFT registry
How the check works
The tool strips spaces, turns letters into capitals and runs five checks in order: characters (letters A–Z and digits only), country code, the length fixed for that country, the structure of the domestic account and the check digits. It stops at the first rule that fails and names it, for example “wrong length: 24 characters expected, 23 entered”.
The check digits are the third and fourth characters. They are tested with MOD 97-10: the first four characters move to the end, each letter becomes a number (A = 10, B = 11 … Z = 35) and the resulting number is divided by 97. A remainder of 1 means the IBAN is consistent. For the registry example RO49 AAAA 1B31 0075 9384 0000 the string becomes AAAA1B31007593840000RO49, then digits only, and the remainder is 1.
The method catches any single wrong digit and nearly every swap of two neighbouring characters, which are the usual mistakes when an IBAN is retyped from an invoice or an email.
What a valid result tells you, and what it does not
A valid result means the IBAN is correctly written. It does not mean the account exists, is open, or belongs to your supplier. Only the bank holding the account knows that.
Invoice fraud uses perfectly valid IBANs: someone alters the account on a PDF invoice or sends a “we have changed banks” email. When a supplier gives you new bank details, confirm them by phone on the number you already had, not the one in the message.
Since 9 October 2025, banks in the euro area check the payee’s name before you authorise a euro payment and warn you when it does not match the IBAN, under Regulation (EU) 2024/886. If your bank shows that warning, stop and ask the supplier.
Paying a Romanian supplier or ANAF from abroad
A Romanian IBAN has 24 characters. After “RO” and the two check digits come four letters that identify the bank (the first four of its BIC), for example BTRL for Banca Transilvania or RNCB for BCR. The tool names the bank only for codes we could confirm from public lists; an unrecognised code does not make the IBAN wrong.
Romanian taxes, duties and social contributions are paid into accounts held with the State Treasury (Trezoreria Statului), whose IBANs contain “TREZ”. The account depends on the type of liability and on the Treasury unit the taxpayer is assigned to; ANAF, the Romanian tax authority, publishes the IBAN lists per Treasury unit. Compare any TREZ IBAN received by email with the official list before paying.
If your company pays Romanian VAT from abroad, the account and the payment reference are settled together with the tax file. We handle this as part of Romanian tax compliance, alongside the returns.
Frequently asked questions
01Does a valid IBAN mean the account exists?
No. Validation only confirms that the IBAN follows the country’s structure and that the check digits match. Whether the account exists and who holds it can be confirmed only by the bank.
02How many characters does a Romanian IBAN have?
24 characters: “RO”, two check digits, four letters for the bank and 16 alphanumeric characters for the account. On paper it is written in groups of four.
03What does TREZ mean in a Romanian IBAN?
TREZ is the code of the Romanian State Treasury. Accounts with this code are used to pay taxes, duties and contributions to the state and local budgets, not to pay companies.
04Is the IBAN I enter stored or sent anywhere?
No. The check runs in your browser; the IBAN never reaches our servers and is not kept. For statistics we record only the outcome (valid or invalid) and the country code, and only if you accepted analytics cookies.
05Do I need the BIC (SWIFT code) as well as the IBAN?
For euro transfers within SEPA the IBAN is enough. For payments in Romanian lei or another currency sent from outside Romania, your bank will usually ask for the payee bank’s BIC too.
Sources and legal basis
- IBAN Registry (SWIFT, registration authority for ISO 13616) — IBAN length and structure for each country; the examples used in the tool’s tests.
- ISO 13616-1:2020 — International bank account number (IBAN), Part 1: Structure of the IBAN
- ISO/IEC 7064:2003 — Check character systems — The MOD 97-10 system used for the check digits.
- ECBS (European Committee for Banking Standards), EBS204 — IBAN: International Bank Account Number — The European implementation standard, with the validation algorithm and examples.
- ANAF — IBAN codes of budget revenue accounts, per Treasury unit (in Romanian) — State Treasury accounts (code TREZ).
- Regulation (EU) 2024/886 on instant credit transfers in euro — Verification of payee, applicable to payment service providers in the euro area from 9 October 2025.
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