Net interest income

Interest earned on loans and investments minus interest paid on deposits and borrowings. It is a bank's core revenue line, before fees and before any credit losses.

A bank earning ₹4,200 crore of interest income and paying ₹2,450 crore of interest expense reports ₹1,750 crore of net interest income.

Growth in the line comes from two places and they behave very differently. More loans at the same spread is volume growth, which is repeatable and consumes capital. A wider spread on the same book is margin expansion, which is usually a function of the rate cycle and reverses.

Decompose the growth before extrapolating it.

Interest earned, less interest paid. That is the business.

Fee income sits alongside and behaves quite differently. Processing fees, distribution commissions on insurance and mutual funds, card interchange and transaction charges all arrive without consuming capital, which makes them the highest-quality revenue a bank earns. A bank whose fee income grows faster than its loan book is improving the shape of its earnings, because it is earning more without needing more equity behind it. The disclosure splits fee income into its components, and the split matters: fees tied to lending volumes disappear when lending slows, while transaction and payment fees do not.