What Is an IBAN and How Do You Check Bank Details Before a Transfer?

An IBAN helps identify a bank account in a standard format, but a plausible-looking number is not enough to make a transfer safe. You also need reliable recipient details and the right instructions for the payment you intend to make.

This guide separates three checks: whether the IBAN has the right structure, whether its checksum passes, and whether the account details genuinely belong to your intended recipient. These checks answer different questions.

1. What an IBAN is used for

IBAN stands for International Bank Account Number. It identifies an account using a standardized structure that includes a country code, check digits, and a national account identifier. This helps payment systems process account details consistently and detect many typing errors.

Not every country uses IBAN. Where it is used, it may be required for domestic payments as well as international transfers. Elsewhere, payment instructions may require a local account number and a routing or bank code. Follow the receiving bank’s instructions and the fields requested for the chosen transfer method.

An IBAN does not itself specify the transfer fee, exchange rate, arrival time, or account currency. Its country prefix also does not establish where the recipient lives.

2. How the structure varies by country

An IBAN contains up to 34 letters and digits. Each participating country has a defined length and national structure; 34 characters is a maximum, not a target for every account.

• First two characters: the country code, written as Latin letters.
• Next two characters: check digits used in the checksum calculation.
• Remaining characters: the national account identifier, called the BBAN. Depending on the country, this can include bank, branch, account, and national check components.

Structure illustration: [country letters] → [two check digits] → [national account identifier]

This diagram contains no bank details and cannot be used for a payment.

For example, German IBANs have 22 characters, British IBANs 22, and French IBANs 27. These are examples of national formats, not statements about TopSend’s coverage. Some national sections contain letters, so an all-numeric rule would reject legitimate IBANs.

Printed IBANs are often grouped with spaces for readability. The electronic form is a continuous string. Preserve leading zeros and never add digits to make an IBAN match another country’s length.

3. IBAN, SWIFT/BIC, and card numbers

An IBAN identifies an account. A SWIFT/BIC identifies an institution and, in some cases, a branch. Depending on the payment route, you may be asked for both. They are not interchangeable, and you should not invent a BIC from an IBAN.

A card number identifies a payment card. It is not an IBAN, even when the card is linked to the same bank account. Entering a card number in an IBAN field will not turn the payment into a card transfer.

A domestic account number may form part of an IBAN, but simply adding a country prefix is insufficient. Obtain the complete IBAN from the bank. For more on bank identifiers, see our separate guide to SWIFT codes.

4. Where to obtain reliable recipient details

Ask the recipient to copy their incoming-payment details from their banking app, online banking, a bank statement, or an official account-details document. Request the account holder’s name as recorded by the bank, the IBAN, and any additional details required for the intended currency and transfer method.

For a business payment, compare the beneficiary name with the invoice and your agreement. If a different company or individual is named, ask for an explanation before proceeding. A familiar logo on a PDF is not proof that its payment details are genuine.

If someone announces new bank details, verify the change through a previously trusted contact channel. Call a number you already know, rather than one supplied in the message announcing the change. Urgency is a reason to slow down.

Share account details only where needed. A sender does not need the recipient’s banking password, PIN, card security code, or one-time login code to send an account transfer.

5. Check the format and checksum

Start with the full IBAN copied from its trusted source. Remove display spaces if the form requires it, and use uppercase Latin letters. Do not silently replace suspicious characters: a Cyrillic lookalike, or confusion between O and 0, should prompt a fresh copy or confirmation.

1. Check that the first two letters correspond to an IBAN country format.
2. Check the exact length and permitted character pattern for that country.
3. Validate the check digits using an IBAN validator from your bank or a trusted payment service.
4. Compare the entire entered value with the source, not just its final characters.

The checksum uses MOD 97. Conceptually, move the first four characters to the end, convert letters to numbers with A = 10 through Z = 35, and calculate the remainder after division by 97. A valid IBAN checksum produces a remainder of 1. Software should also check the country’s structure, rather than relying on this calculation alone.

A correct checksum does not confirm that the account exists, is open, accepts the intended payment, or belongs to the named recipient. Fraudulent instructions can contain a mathematically valid IBAN. Where a bank or provider offers a beneficiary-name check, review its result separately and resolve any mismatch before confirming.

6. Use this checklist before sending

1. Confirm that the selected transfer method actually asks for an IBAN.
2. Obtain current details and the account holder’s bank-recorded name.
3. Check the country format, length, characters, and checksum.
4. Verify any changed instructions through a trusted channel.
5. Confirm the account currency and any required BIC, reference, or additional bank details.
6. Review the full IBAN, beneficiary, amount, currency, and displayed terms on the final screen.

Common errors include copying an old invoice, losing leading zeros in a spreadsheet, using a card number, or leaving a character out when typing manually. Copying usually reduces typing mistakes, but still compare the pasted result with the original.

If validation fails, do not guess a correction or alter the check digits yourself. Request fresh details. If you have already sent a payment with incorrect details, contact the sending bank or service promptly and ask about tracing, correction, or recall. Recovery is not guaranteed.

7. Frequently asked questions

Does a valid IBAN prove who owns the account?

No. Format and checksum checks cannot establish ownership. Verify the recipient independently and consider any available beneficiary-name check.

Can I find the account currency from the IBAN?

No. Ask the recipient or receiving bank which currency and incoming-payment instructions apply to that account.

What if the recipient has no IBAN?

Their banking system may use other identifiers. Request official incoming-payment instructions and check whether your chosen transfer method supports those details. Do not construct an IBAN yourself.

Should I send a small test payment?

Where available and appropriate, a test can help confirm receipt, but it may involve fees and does not replace identity checks. Verify receipt with the intended recipient through a trusted channel.

How should I apply this when considering TopSend?

Open TopSend and review the available methods, required recipient details, and current terms for your intended transfer. Do not assume an IBAN-based method is available solely because the recipient has an IBAN.