Glossary
MID
Merchant ID: the number that identifies one merchant account at the acquirer. Card networks count chargebacks and fraud per MID, which is why grey offers spread sales across many of them.
Also called: merchant ID, merchant identification number, merchant number.
Every transaction carries the MID of the account that processed it, and monitoring programs such as Visa's VAMP and Mastercard's ECM calculate dispute ratios against it month by month. A business can legitimately hold several MIDs, for example one per brand or currency.
Spreading the same merchant's sales across many MIDs to keep each under the thresholds is load balancing, and card networks treat it as evasion. In the FTC's 2026 case against Humboldt Merchant Services, shell companies opened more than 1,000 accounts for nutra advertisers, and CRMs routed transactions to the MIDs with the best approval rates.
When a trial or CC-submit offer suddenly approves much better or much worse, the advertiser may have switched MIDs. Ask your manager whether the offer runs on a single account or several.
Related terms: Merchant account, Load balancing, VAMP, CC submit, Approval rate.