What is a merchant ID? Tom Woodward May 29, 2016 14:47 Follow Each MyGate merchant is issued with a MyGate Merchant ID. This identifies the merchant on MyGate's Back Office system. Related articles What is and how do I find my Merchant ID What is a referral URL and how do I add one? What is EFT Secure? What is an application ID? Comments 0 comments Please sign in to leave a comment.