Merchant ID (MID)
A unique identifier assigned by acquiring banks to each merchant account, used to route transactions, track processing activity, and attribute fees across the payment processing system.
A Merchant ID (also called Merchant Identification Number) is typically a 15-digit alphanumeric code that identifies a specific merchant account within the payment processing network. The MID appears on processing statements, terminal configurations, and transaction reports. When transactions are processed, the MID tells the card networks and acquiring banks which merchant account should receive the funds and be charged the associated fees.
Businesses with multiple locations, business units, or processing needs may have multiple MIDs under a single corporate entity. This multi-MID structure offers several advantages including separate reporting for each location or division, enabling better analytics and accounting, different merchant category codes for distinct business lines, location-specific settlement for franchise models, and isolated risk management where one location's chargeback issues don't affect others. However, some processors charge additional fees for multiple MIDs, and managing multiple accounts adds administrative complexity.
The MID structure also affects chargeback ratio calculations and risk assessment. Card networks monitor chargeback ratios at the MID level, meaning high-volume locations can potentially benefit from standalone MIDs that isolate their performance. Conversely, consolidating low-volume locations under a single MID may be more cost-effective despite combined reporting. MIDs are essential during transaction disputes, as they identify which specific merchant account processed a transaction and where chargebacks or retrieval requests should be directed.
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3D Secure
An authentication protocol for online card transactions that adds an additional verification layer between the cardholder and issuing bank, shifting fraud liability from merchants to card issuers when properly implemented.
ACH Payment
Automated Clearing House payment is an electronic bank-to-bank payment method that transfers funds directly between bank accounts through the ACH network, typically used for direct deposits, bill payments, and recurring transactions.
Acquirer
A financial institution that processes credit card payments on behalf of merchants, maintains merchant accounts, and facilitates the settlement of funds from card-issuing banks to merchant bank accounts.
Address Verification Service (AVS)
A fraud prevention tool that compares the numeric portions of a billing address provided during a transaction against the address registered with the card-issuing bank, returning match result codes to help merchants assess transaction risk.
Aggregator
A payment service provider that enables multiple merchants to process card transactions under a single master merchant account rather than each merchant having their own dedicated merchant account, common with services like Square, Stripe, and PayPal.