An acquirer reference number (ARN) is a numeric code attached to a card transaction by the acquiring bank during processing. It travels with the transaction through the entire card network, and every party along that path can use it to pull up the same record. Refunds are where this comes up most.

When money doesn’t land in a customer’s account within the expected timeline, customer service teams at the issuing bank use the ARN to locate it. Below, we’ll discuss how an ARN gets generated, what its format looks like, and how to use one to trace a refund that hasn’t shown up yet.

Key takeaways

• An acquirer reference number (ARN) identifies one specific transaction, and refunds always generate a separate ARN from the original charge.

• ARN format varies between Visa and Mastercard, so the same 23 digits encode different information depending on the network.

• Since issuing banks apply credits on their own schedules, an ARN helps trace a refund but doesn’t speed up settlement.

What is an acquirer reference number (ARN)?

An ARN is a numeric code the acquiring bank attaches to a card transaction the moment it processes the transaction. That number stays with the transaction as it moves through the card network, from the acquiring bank to the network to the issuing bank holding the cardholder’s account.

How are acquirer reference numbers (ARNs) generated and assigned?

The acquiring bank generates the ARN only once, the moment it processes the transaction. It doesn’t reissue or reassign the ARN later, even if the transaction’s status changes afterward. The ARN is tied to the transaction, not the account. That means a single card can rack up dozens of ARNs over time, one for every purchase, refund, or reversal tied to it. And refunds get their own ARN; they’re not traced using the same ARN as the original purchase. Because it’s a separate transaction moving in the opposite direction, the card network assigns it a new number.

What does an acquirer reference number (ARN) format look like?

An ARN is a 23-digit number, but its internal structure shifts depending on which card network issued it. Visa and Mastercard each encode a different set of details inside that string.

A typical Visa ARN breaks down like this:

• Acquiring bank identification number: A six-digit segment that identifies which acquiring bank processed the transaction

• Julian date: A four-digit segment that represents the year and day of year the transaction processed

• Sequence number: A six-digit running count that separates this transaction from every other one the acquirer processed that day

• Remaining digits: Typically reserved for terminal or source system identifiers, which vary depending on how the acquiring bank structures its own systems

Mastercard’s ARN runs the same total length but organizes the segments differently. It often prioritizes a Banknet Reference Number (BRN) sequence ahead of the date fields. Neither network publishes its full specification for public use, and the exact position of each segment can shift depending on how the acquiring bank implements it.

An ARN isn’t meant to be decoded by a person. It’s built to be read by a bank’s system in order to pull up the transaction it’s attached to. ARNs must be entered correctly because a single transposed digit points to a different transaction entirely.

How does acquirer reference number (ARN) tracking work for a refund?

Locate the refund’s ARN from the payment provider’s dashboard or application programming interface (API), where it’s typically listed next to the refund’s status and amount. Then confirm the refund processed on the business’s end; don’t assume the issuing bank is holding it. Give the customer the ARN and have them call the number on the back of their card to provide that reference number directly to their bank’s support team. Ask the bank for a pending or in-transit status. A representative can search for the ARN in the bank’s own system and confirm the credit is moving even before it posts as a visible transaction.

Refunds typically take 5–10 business days to post because card networks settle in batches and issuing banks apply credits on their own schedule; weekends and bank holidays add to that window.

Does Stripe provide ARN data for refunds?

Stripe attaches an ARN to a refund once the card network returns it, which typically takes a few days. Businesses can find the ARN in a couple of places:

• Stripe Dashboard: Open the refund’s detail page, where the ARN appears alongside the refund’s status, amount, and processing date, once the acquirer has returned the funds.

• Refunds API: Retrieve the ARN programmatically once it’s available; this helps support teams retrieve it automatically instead of looking it up manually for every case, which matters for businesses fielding a high volume of refund questions.

What should you do if an acquirer reference number (ARN) doesn’t resolve a refund issue?

An ARN doesn’t guarantee an instant answer; set that expectation with the customer up front. Some issuing banks take longer than others to index a refund against its reference number. A representative on the phone might say the number isn’t showing up even though the refund is still in transit, which makes it a timing issue, not a lost refund.

If the standard refund window has passed—generally 5–14 business days—and the issuing bank still can’t locate the transaction with the ARN, then advise the customer to open a formal inquiry. Suggest they escalate the case with their card issuer if frontline support can’t locate the transaction, since issuers have internal paths built for exactly this situation.

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FAQs about acquirer reference numbers (ARNs)