How FD Interest Is Calculated (Quarterly Compounding Explained)

Fixed deposits remain one of India’s most popular ways to save — predictable, simple and safe. Yet many depositors don’t know how their interest is actually calculated, or why two FDs with similar rates can pay slightly different amounts. It comes down to compounding.

The FD formula

For a cumulative FD (where interest is reinvested), banks use the compound interest formula:

A = P × (1 + r / n)^{n × t}

• A — maturity amount
• P — deposit amount
• r — annual interest rate as a decimal
• n — compounding periods per year (4 for quarterly)
• t — tenure in years

Why quarterly compounding matters

Every three months, the bank adds that quarter’s interest to your balance. From the next quarter, you earn interest on that interest too. Here is the same deposit with different compounding:

The difference isn’t huge, but it adds up on larger deposits and longer tenures.

Headline rate vs effective yield

Because of quarterly compounding, a 7% FD actually earns about 7.19% a year in effect. This is called the effective annual yield:

Effective yield = (1 + r / n)ⁿ − 1

When comparing a bank FD with, say, a bond or a scheme that compounds yearly, use the effective yield so you are comparing like with like.

Cumulative vs non-cumulative FDs

If you choose monthly payouts, the bank often pays a slightly lower discounted rate, because you receive the money earlier.

Tax and TDS

• FD interest is taxable at your income-tax slab rate in the year it is earned (even in a cumulative FD where you receive it only at maturity).
• TDS is deducted by the bank when your interest crosses the threshold for the year. The thresholds differ for senior citizens and have been revised in recent budgets, so check the current limits.
• If your total income is below the taxable limit, you can submit Form 15G (or Form 15H for seniors) to avoid TDS.
• TDS is not an extra tax — it’s an advance. It shows in your Form 26AS and is adjusted when you file your return.

Tips to earn more from FDs

1. Compare rates across banks — small finance banks and some private banks often pay more (check deposit insurance coverage, which protects up to ₹5 lakh per depositor per bank).
2. Senior citizens usually get 0.25–0.50% extra.
3. Ladder your FDs — split money across different maturities so some cash becomes available every year, and you can reinvest at newer rates.
4. Avoid breaking FDs — the premature withdrawal penalty can cost more than you expect.

Calculate your maturity amount

Our FD Calculator lets you enter the amount, rate, tenure in years and months, and compounding frequency, then shows the maturity value and interest earned instantly.

Written by the Toolsopedia team. Spotted an error? Tell us and we’ll fix it.