How to check a bank account number is valid?

Read time: 3 mins

Last updated: 17 July 2024

In the UK and Ireland, each bank account number is created using a unique algorithm specific to each bank, and sometimes to individual branches within a bank. These numbers are not generated sequentially; the generation system is designed to minimize similarities that could lead to errors in transferring money to the wrong account.

For instance, a branch might create an account number "12345678", but it would avoid generating a number like "12354678".

Whether you're sending money via BACS or Faster Payments, or setting up customer Direct Debits, having a step to check bank account and sort code data is essential.

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How does it work?

Banks use "modulo" and "double-alternate" modulus checker algorithms, along with specific "weights" to perform calculations. These methods help ensure account numbers are entered correctly by identifying common errors such as swapped digits.

As new banks emerge and new sort codes are assigned, the relevant algorithms must be shared with other banks. Mintly keeps its system up-to-date with the latest algorithms, providing customers with current data.

There are multiple methods to verify if an account number and sort code are valid. One approach involves obtaining the directory of sort codes and implementing the necessary algorithms and weight databases to perform the checks, which must be updated regularly with new data. A lookup table can also be used to verify a bank sort code, requiring consistent updates as new data becomes available.

Alternatively, you can use a service like Mintly. Our database receives weekly updates with the latest data and algorithms. Our stable API allows you to query a sort code and account number, confirming their validity and the types of payments the branch supports. Integration with existing systems is straightforward.

Lady checking sort code and account number are valid

Need a bank account verification solution for your business?

If you're in need of an online sort code and account number checker, our tools offer unlimited checks. You can also use our free tool to check up to five accounts daily at no cost. For requirements involving faster payments, BACS, or Direct Debit, Mintly tools are an excellent choice.

To use our bank sort code and account number checker, simply log in to our web UI and submit the details. Our fast service will provide the answer, including the bank branch's name, location, and contact information based on the sort code, and confirm whether the account number is valid. Please note that while the algorithms can verify validity, they do not confirm if the account is active.

In addition to verifying sort codes and account numbers, Mintly also has an IBAN checker (International Bank Account Number) and SWIFT codes checker for international money transfers.

Automation - the next step to saving more money

For businesses wanting to automate their processes and integrate a sort code lookup or bank account modulus check into their own systems, Mintly offers an API (Application Programming Interface) that allows systems to talk to each other over the internet securely. Our API sends back all the bank details once validated, so that you can handle the next step in your workflow.

If you'd like to try Mintly out, we have a 14 day free trial for all our plans, or if you have further questions, please get in touch, we'd love to help you with your bank validation needs. Or book a demo with one of our experts, who are happy to help you get set up.