The interest on your balance is calculated daily and then paid directly into your account monthly – starting from the day you open your account. If you have a pending outbound payment that hasn’t been processed by the end of the day, you’ll earn interest on that amount until it’s cleared.  

The rate you’ll earn is fixed for a year, starting from the date you open your account and there’s no limit on how much interest you can earn. You can check your rate in your bank account terms.