Every quarter, interest trickles into your savings account — usually 2.7 to 3.5 per cent a year from a large Indian bank — while that same bank lends money out at 9 to 14 per cent. That gap is not an oversight; it is the heart of how banks make money. Once you understand the business behind your savings account — the net interest margin, fee income and the economics of deposits — you will also understand why your savings earn so little, why banks push credit cards and personal loans so aggressively, and where a bank’s profits genuinely come from.

What NIM is, and why bankers obsess over it

Net interest margin, or NIM, is the difference between the interest a bank earns on loans and investments and what it pays on deposits and borrowings, expressed as a percentage of its interest-earning assets. If a bank earns 9 per cent on its loan book and pays 5 per cent on deposits, the raw spread is 4 per cent — but after adjusting for assets that earn nothing, like cash reserves with the RBI, reported NIM usually lands between 3 and 4 per cent for Indian banks. It is the largest line in most banks’ profit statements, which is why analysts track every quarterly basis-point move. The deposit mix matters enormously: a bank funded mostly by cheap current and savings deposits — the famous CASA ratio — pays far less for its raw material than one reliant on expensive bulk deposits.

The second engine: fees, commissions and other income

Interest is only part of the story. The second engine is fees: account maintenance and debit card charges, SMS alerts, cash-handling and locker fees, loan processing and prepayment charges, credit card fees and late penalties, foreign-exchange markups — each small per customer, enormous in aggregate. Then there is commission income from selling mutual funds and insurance, merchant fees on card transactions, and charges for guarantees to corporate clients, plus volatile treasury gains from trading securities and forex. For many large private banks, non-interest income is now a quarter to a third of total income — which is why your relationship manager keeps calling about insurance: distribution commission is high-margin revenue needing no capital, unlike lending.

Where your savings account fits in the machine

Your savings account is, from the bank’s perspective, raw material — among the cheapest funding available at 2.7 to 3.5 per cent on daily balances. The bank deploys it into home loans at 8.5 to 9.5 per cent, personal loans at 11 to 14 per cent and credit card receivables at 36 to 42 per cent annualised; the difference, after defaults, operating costs and regulatory reserves, is the profit. That is why banks compete so fiercely for your salary account: a customer with steady balances who uses the bank’s cards, loans and investment products delivers cheap deposits plus fee income plus lending margin. The savings account itself is often a loss-leader — but it is the gateway to everything profitable that follows.

Why loans cost you so much more than deposits earn

The spread looks unfair until you see the costs hidden inside it. First, defaults: a portion of every loan book goes bad, and banks must set aside provisions for non-performing assets, which eats directly into the margin. Second, regulation: banks must keep 4.5 per cent of deposits as cash reserve ratio with the RBI earning nothing, hold 18 per cent in statutory liquidity ratio securities, and direct 40 per cent of lending to priority sectors such as agriculture and small businesses at thinner margins. Third, operating costs: branches, staff, technology and compliance are expensive, and India’s cost-to-income ratios remain high by global standards. What looks like a 6-percentage-point spread between your savings rate and a personal loan rate shrinks dramatically after these costs — which is why NIM, not the raw spread, is the number that matters.

How to read a bank’s health from these numbers

You do not need to be an analyst to use these concepts. A stable or rising NIM with a high CASA ratio suggests a bank with cheap funding and pricing power. Fee income growing faster than the loan book suggests a bank deepening customer relationships rather than just chasing loan growth. And if a bank offers you a savings rate far above the market, ask how it funds that generosity — it may be paying up for deposits because it needs to grow its loan book fast, which is worth knowing before you park large sums there.

• NIM (3–4% typical): the core lending margin; stable or rising is healthy.
• CASA ratio: share of cheap current and savings deposits; higher means cheaper funding.
• Fee income share: non-interest income diversifies earnings beyond lending cycles.
• Credit costs: provisions for bad loans; the silent killer of the margin.

FAQs

Why does my savings account pay only 3 per cent? Because banks can attract deposits at that rate — most customers prioritise safety and convenience. Sweep-in FDs, liquid funds or small finance banks pay more, with trade-offs.

Do banks make money when I just keep money in savings and do nothing? Yes, modestly. Your deposit funds loans earning far more than the interest paid to you, though servicing your account also costs the bank money.

What is the difference between NIM and spread? Spread is the simple difference between average lending and deposit rates. NIM divides net interest income by average interest-earning assets, so it accounts for funds that earn nothing, like cash reserves.

The next time you see a few hundred rupees of savings interest credited, remember the machine behind it: your deposit is the cheapest raw material in finance, converted through lending, fees and scale into one of the most consistent profit engines in the economy. Knowing how banks make money will not raise your interest rate — but it will make you a sharper negotiator every time a bank tries to sell you something.

Compiled by the Khabar 24h Editorial Desk from publicly available sources.