Interest is calculated daily, based on the total balance of your 1 Year Fixed Rate, and money you add during the funding window starts earning interest the next working day after your payment is received.
Your interest rate is fixed, and you can see your daily interest in Wealth > 1 Year Fixed Rate > Earnings.
Once your 1 Year Fixed Rate reaches the end of its term, the interest you’ve earned is paid out and you can access your money on the access date shown in the app. You can find out more about what happens when your Fixed Rate matures here.