Xena pays a 0.03% (3bp) rebate to liquidity makers. Rebates are collected during the day and deposited to your account at midnight (UTC).
Rebates are given in the same currency as the fee currency (BTC or USDT depending on the trading pair). After your rebates are settled to your account, you can use them without any limitations (trade or withdraw them).
During the day you can check your outstanding in the Balance page:
The history of payments is located on the Balance operations history page: