In SDs, your interest is calculated each day on pro-rata basis and credited at the closure of SD. Example if you have ₹50,000 added into your SD for a 1 year duration at an interest rate of 5.4%, then the daily interest rate pro-rata is roughly ₹7.39. If you add additional ₹50000, the new daily interest rate pro-rata would be ₹14.78. The final interest amount will be aggregated and transferred at the closure of SD to your Savings Account.