Business Managing money

What is an Acquirer Reference Number (ARN)?

Saim Jalees

24.08.26 (last updated)

Read time 5 minutes

Waiting for a refund that never seems to arrive, or spotting a card transaction you don’t recognise, can be frustrating — especially when you don’t know how to investigate it.

For card payments, an Acquirer Reference Number (ARN) can help your bank trace a transaction through the payment network. It’s particularly useful when following up on a delayed refund, checking a payment’s status or supporting a dispute.

This guide explains what an Acquirer Reference Number (ARN) is, how it works and the exact steps UK residents can take to find and use one to track payments and resolve disputes.

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Acquirer Reference Number (ARN) information at a glance

Topic	Notes
What is an Acquirer Reference Number (ARN)?	A unique tracking code assigned by the merchant's bank to credit/debit card transactions, acting as a universal reference for both banks involved in the payment².
Why You Might Need an ARN in the UK	Used for tracking delayed refunds, disputing unrecognised transactions, following up on failed payments, or providing proof of a processed payment¹.
How to Get an ARN in the UK	Request it from your bank/card issuer or the merchant. Provide transaction details (date, merchant, amount) to help locate it¹.
Role of Banks and Card Issuers	The merchant's bank generates the ARN, while your bank acts as your point of contact and communicates with other institutions¹.
ARN for Tracking and Disputes	Functions like a tracking number for payments and is a key reference in dispute resolution processes².

What is an acquirer reference number (ARN)?

An Acquirer Reference Number, or ARN, is a unique code assigned to any transaction made with a credit or debit card². Think of it as a tracking number for your payment as it moves through the banking network.

When you make a purchase, the payment travels from your bank (issuer) to the merchant’s bank (acquirer). The acquirer assigns the ARN—typically around 23 digits for Visa and Mastercard—which becomes the shared reference for both banks.

Its purpose is to help track transactions. If an issue arises, such as a delayed refund, the ARN enables banks to locate and verify the payment status efficiently³.

Why you might need an ARN number in the UK

For UK residents, there are several common situations where an ARN can be useful.

Situation	How an ARN can help
Tracking a delayed refund	This is one of the most common uses of an ARN.¹ If a merchant confirms a refund but it hasn’t appeared, the ARN can help your bank trace the payment.
Disputing an unrecognised transaction	If you see a transaction you don’t recognise, your bank may use the ARN to investigate and communicate with the merchant’s bank.²
Following up on failed or complex payments	For international or high-value payments, an ARN helps identify where a transaction may have been delayed or interrupted.³
Providing proof of payment	An ARN can serve as confirmation that a transaction was processed by the merchant’s bank.³

How to get an ARN number in the UK

You cannot locate an ARN yourself¹. Instead, you need to request it from your bank or the merchant.

Step	What to do
1. Identify the transaction	Gather details such as the date, merchant name and amount.⁶
2. Contact your bank	Reach out using official customer support channels and explain the issue clearly.
3. Request the ARN	Ask your bank to trace the transaction and provide the ARN. In some cases, the merchant may supply it.¹
4. Wait for confirmation	It may take a few business days for your bank to retrieve the ARN.

The role of the bank and card issuer in ARN transactions

Party	Role
Merchant’s bank	Generates the ARN.²
Your bank or card issuer	Acts as your main point of contact and communicates across the payment network on your behalf.³
Acquiring bank	You typically can’t contact this bank directly. Your bank communicates with it on your behalf.³

Understanding ARN number tracking and dispute resolution

An ARN provides a consistent reference across banking systems. When you provide it to your bank, they can use it to check the transaction status within card networks like Visa or Mastercard¹.

In disputes, such as chargebacks, the ARN is used to ensure all parties are referencing the same transaction².

Clarifying ARN numbers against other references

	Merchant Reference	Bank Transaction ID	ARN
Purpose	Internal seller tracking³	Internal bank reference	Cross-bank transaction tracking²
Who uses it	Merchant	Your bank	Both banks

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Sources:

Sources last checked on 30 March 2026

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