The annoucement can be found below :
" Fellow Binancians,
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.
Thanks for your support!
Binance Team
2018/05/18
Find us on
Telegram: https://t.me/binanceexchange
Twitter: https://twitter.com/binance "
Source: Binance