The service fee remains the same - 0.5% of the transfer amount for verified and premium accounts. For unverified accounts the fee is 1.99% of the transfer amount. The fee is always deducted from the account balance of the sender.
How does the system choose an account to send money from?
The system selects an account with sufficient funds. If a user has several accounts with sufficient balances, the system will ask the user to make this choice.