ARN (acquirer reference number)
The identifier a transaction carries through the scheme network, used to trace one specific payment or refund between the acquirer and the issuer. It is what a merchant is asked for when a customer says a refund never arrived: with it, the customer's own bank can find the money.
Why it matters to a merchant
Ask for it the first time a customer says a refund has not arrived, rather than the third. Nine times in ten the refund was processed and is sitting somewhere the customer has not looked; with this number their own bank can find it in minutes, and without it the conversation goes in circles for a week.
Read more: Refunds and voids: three things that are not the same
Where this comes up
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Related terms
In this section: How a payment moves