Binance will double referral commission rewards to 40% for all accounts that hold 500 BNB or more, starting from 2018/05/19 0:00 AM (UTC).
Each user’s commission rate will then be adjusted at 0:00 AM (UTC) each day based on their BNB holdings.
The commission rate for all other users will remain at 20%.
Note: The daily snapshot of BNB holdings will not include any BNB locked in-order or pending for withdrawal/deposit.
https://www.binance.com/?ref=21211888