How an Acquirer Reference Number Works for Businesses

An acquirer reference number (ARN) is a unique identifier attached to debit and credit card transactions that gives store owners, payment processors, and banks a common tracking reference. 

When a customer has questions about a refund on a card purchase, an ARN can help you track down the transaction and provide answers. Shopify Payments provides ARNs for Visa and Mastercard transactions, and they appear in the order timeline in your admin dashboard. If a refund hasn’t reached a customer’s account as expected, you can provide them with an ARN to share with their bank; their bank can trace the transaction to investigate the delay.

Learn what an acquirer reference number is, how ARNs work, and how they differ from other transaction identifiers.

What is an acquirer reference number?

An acquirer reference number (ARN) is a unique identifier assigned to debit and credit card transactions as they move through your payment flow. ARNs are commonly associated with Visa and Mastercard transactions and are designed to let the parties involved in a payment identify and track it.

An ARN ranges from 8 to 30 digits and conveys payment details and other information that helps identify the transaction, such as the card network, acquiring institution, processing date, and a sequence number that distinguishes the transaction from others. The length and format can vary depending on the card network and payment system.

The acquiring bank—the financial institution that handles card transactions on behalf of the store owner—generates the ARN during the clearing process after the transaction has been authorized. From this point, the store owner, card-issuing bank, and processing network can track the payment using the ARN.

ARNs help store owners when a customer has a question about a refund. For example, if a customer tells you that their refund credit isn’t showing in their bank account after several days, you can give them the acquirer reference number, which they can provide to their bank. Their bank can then use the ARN to trace the refund. 

Other common use cases include:

• Dispute defense. You can show that the refund was sent to the card network.

• Reconciliation. The ARN helps match a refund with the original transaction.

• Escalations. Customer support can provide the ARN to help a bank or payment provider investigate a missing refund.

Other types of payment reference numbers

Visa and Mastercard transactions use ARNs. Other networks may use different transaction identifiers or may not make an ARN available through the merchant’s payment provider. Here are a few other transaction identifiers you may encounter: 

• Retrieval reference number (RRN). An RRN is a unique 12-character identifier that the acquiring bank assigns to a credit or debit card transaction to help all parties involved track the status of a payment.

• System trace audit number (STAN). A STAN is a six-digit code that cardholder banks use to identify card transactions, usually within the Discover card network. 

• Provider-specific transaction ID. Payment providers may assign their own identifiers to transactions to help businesses find, manage, and reconcile payments within the provider’s system. However, these IDs are separate from reference numbers used to trace transactions between financial institutions.

How an acquirer reference number works

Here’s the sequence following a card payment from authorization to settlement and how the ARN fits into the card payment process: 

1. The customer makes a payment. When a customer initiates a card payment, the store’s payment gateway sends an authorization request to the payment processor. The request goes through the card network to the customer’s issuing bank, which approves or declines the transaction.

2. The business captures the payment. After authorization, the business’s payment processor captures the approved transaction, signaling that the payment should move forward.

3. The transaction moves to clearing and settlement. The card network sends the transaction details between the issuing and acquiring banks. The banks settle the funds when the business’s bank assigns an ARN. 

4. The ARN follows the transaction. Once the ARN is assigned, the parties involved have a shared reference they can use to locate and trace the payment.

How to find an ARN in Shopify

If you process a Visa or Mastercard refund through Shopify Payments, you can find the associated ARN in your Shopify admin dashboard. The ARN is especially useful if a customer hasn’t received their refund and needs help tracking it down.

Here’s how to find it:

1. Locate the refunded order. From your Shopify admin dashboard, go to Orders to see your order timeline. Refund details are recorded in the order timeline, giving you a central place to check payment activity and find information you may need to resolve customer questions. 

2. Find the refund in the order timeline. In the order timeline, find the transaction and open the refund details. For Visa and Mastercard transactions, this is where you will find the ARN associated with the refund.

3. Share the ARN if the customer needs help. If the refund hasn’t arrived as expected, give the ARN to the customer and advise them to refer to it when they contact their bank or card issuer. The customer’s bank can use the ARN to trace the refund and investigate where the funds are located. 

With Shopify Payments, refunds can remain pending for up to two business days while the funds are processed back to the customer. Depending on the customer’s bank, it can take as long as 10 business days for the refund to arrive.