Fiat Denomination: When paying an invoice in fiat currency, rates are calculated in real-time. To ensure the recipient gets the required amount even when exchange rates are changing before the transaction is confirmed, we request a small extra amount. Any excess funds are automatically refunded to the payer.

Swaps: When converting one cryptocurrency to another (e.g., DAI to USDT), minor price changes can occur during the swap. To ensure the recipient gets the required amount, we ask for a little extra. Any excess funds are automatically refunded to the payer.