How a merchant ID works
The acquirer issues the MID when the merchant account is approved, and the gateway or terminal is configured with it. In card messages the value travels in the card acceptor ID field.
The format is the acquirer's own. There is no global register of MIDs, and the same business has a different MID at each acquirer. Below the MID sit terminal IDs, one for each device or checkout.
Why a merchant has several merchant IDs
- One for each acquirer the merchant uses
- One for each currency or legal entity
- Separate IDs for in-store, online and recurring payments
- Separate IDs for lines of business with different category codes
What a merchant ID means for a platform
Acquirers watch dispute and fraud ratios merchant by merchant, so how payments are spread across MIDs affects what the monitoring shows. A gateway that connects several acquirers stores each merchant's MIDs and routes every payment to one of them, and reconciliation matches settlement files back by MID.
A payment facilitator works differently. Its sub-merchants usually share the facilitator's MID at the acquirer and are told apart by a sub-merchant identifier in each message.
Merchant ID, terminal ID or category code?
- Terminal ID
- Identifies one device or checkout under a merchant ID.
- Merchant category code
- Classifies the kind of business. Many merchants share one category code, and no two share a merchant ID at the same acquirer.
- Card acceptor ID
- The name of the message field that carries the merchant ID.
Where a merchant ID shows up in a platform
Modules that do the work
- Merchant onboardingBusiness sign-up, verification and underwriting, from application to first payment.
- Card acquiringCard acceptance on the phone, in store and online, through the acquirer you choose.
- BackofficeOne console to run the platform: customers, money, risk, content and staff permissions.
- LedgerThe double-entry book of record behind every balance, fee and transfer.