The headline compounds monthly. Effective yield is (1 + rate ÷ compounding periods)periods The headline compounds monthly. How often interest compoundsminus; 1, with daily compounding over 365 days a year. How often interest compounds changes the result far less than the rate or the time — the three rows show it. Interest is shown before tax, at one rate for the whole period, with nothing added or withdrawn. Indicative only. Not financial advice.