Short answer: GMX referral codes are registered on-chain, and the rebate depends on a tier: Tier 1 is open to anyone with a 5% reward and 5% discount, while Tiers 2 and 3 require weekly volume and active users. Rebates apply to opening and closing fees only, not to borrow or funding fees.
A code that lives on-chain
A GMX referral code is registered in a transaction from the Referrals page, under the Affiliates tab. Codes can use letters, digits or underscores, are case-sensitive and can be up to 20 characters. The documentation recommends registering on Arbitrum for the fastest and least ambiguous setup.
Because the code is on-chain, attribution does not depend on cookies. A trader attaches the code and receives the discount, and the affiliate reward is tied to that trader’s activity.
The three public tiers
Tier 1 is open to anyone: 5% discount for the trader and 5% reward for the affiliate. Tier 2 requires 15 or more active users and 5 million dollars or more of combined weekly volume, and pays 10% on both sides. Tier 3 requires 30 or more active users and 25 million dollars or more of weekly volume, with a 10% discount for the trader and a 15% reward for the affiliate, paid in the market’s collateral token.
Partner tiers, such as Tier 4, are assigned case by case by GMX Partners and have no public thresholds.
What the rebate does not cover
Rewards and discounts apply to opening and closing fees for leverage trading. They do not apply to borrow fees or funding fees, which is where a lot of the cost of a long-held position sits.
So the benefit of a code is largest for strategies that trade often and hold briefly, and smaller for positions held for days.