How Is Fixed Deposit Interest Calculated?
Two people book a fixed deposit on the same morning. Same bank. Same amount, same tenure, same headline rate on the rate card.
One of them opens an NRE deposit from Dubai. The other opens a USD deposit at a GIFT City banking unit. Twelve months later, their maturity amounts do not match.
Neither of them was cheated. They simply ran into the part of a fixed deposit that almost nobody reads.
The headline rate is not the calculation. It is only one input into the calculation.
At Belong, we get this question in our WhatsApp community more often than any other deposit question. Not "which bank pays most", but "why is my number different from what I expected".
The answer is almost always sitting in the fine print of the deposit advice.
This guide walks through the actual machinery. What the bank multiplies, how often it compounds, which calendar it counts against, and where tax enters the number.
The short answer
A bank calculates fixed deposit interest using four things.
The principal you deposited. The rate that applied on the day the deposit was funded.
The number of days the money stays, measured against a defined year length. And the frequency at which earned interest is added back to the principal.
Change any one of those and your maturity amount changes. The headline rate is only the second item on that list.
👉 Tip: Ask your bank for the "effective annualised yield" on a cumulative deposit, not just the card rate. Most banks publish both.
The two engines: simple and compound
Every deposit calculation runs on one of two engines.
Simple interest pays you on the original principal only. Your earned interest sits idle. It does not go on to earn anything itself.
Compound interest adds earned interest back to the principal at fixed intervals. The next interval then calculates on a larger base. This is compounding, and it is where longer deposits quietly pull ahead.
The interest rate on the card tells you nothing about which engine applies. Which engine your deposit uses is not your choice alone. It depends on tenure and on the payout option you selected.
Kotak Mahindra Bank states plainly that deposits below 181 days are calculated as simple interest at maturity. Bank of Baroda notes the same principle for deposits shorter than one quarter. Those short deposits are counted on actual days.
Dial one: the principal that actually earns
This sounds obvious. It is not always.
Your deposit starts earning on the date the bank receives clear funds, not the date you clicked submit. ICICI Bank's GIFT City banking unit spells this out in its deposit terms. The deposit date is the later of the funds landing or the documentation being received.
For an NRI funding a deposit through an inward remittance, that gap can run several working days. You lose those days of interest. Nobody tells you, because technically nothing went wrong.
👉 Tip: Wiring funds to book a deposit? Ask the bank to confirm the value date, not the instruction date.
Dial two: the rate that actually applies
Banks apply the rate that was in force on the day the deposit was funded. That rate then locks for the full tenure of the deposit.
This is why two deposits booked days apart can carry different rates. It is also why chasing a rate you saw last week can end in disappointment.
Something material changes here from October 2026. On 30 July 2026, the Reserve Bank of India issued fresh amendment directions on deposit interest rates.
Reporting on those directions notes a new uniformity requirement. Banks must offer the same rate across all branches for similar deposits accepted on one day.
The same reporting notes that the framework also covers rupee deposits of non-residents. That means NRE and NRO deposits sit inside this transparency requirement too.
Before you compare anything, pull live rates rather than remembered ones. Our NRI FD rates explorer is built for exactly that comparison. The NRE FD interest rates guide explains what drives the differences.
Dial three: the day count basis
Here is the input almost every FD article skips.
Interest is a daily quantity. To get a daily figure, the bank divides the annual rate by a year length. That assumed year length is not always 365 days.
State Bank of India's deposit terms cover the broken period after completed quarters. Interest there is calculated on a 365 day basis. Bank of Baroda applies 365 or 366 days for rupee deposits shorter than a quarter.
Foreign currency deposits work differently. Bank of Baroda's published terms state that FCNR interest is calculated on a 360 day year. ICICI Bank's GIFT City unit says the same for deposits in USD, EUR, AED, CHF and JPY.
The same unit uses a 365 day year for deposits in GBP, SGD, CAD, HKD and AUD. So the currency you choose changes the denominator.
Why this matters: dividing an annual rate by 360 instead of 365 produces a slightly larger daily figure. Over a full year, that gap works out to roughly 1.4 percent more interest days.
Not on the rate. On the count.
That is small on a modest deposit. On a large USD deposit held for years, it stops being small.
👉 Tip: Comparing a rupee FD against a USD deposit? Check the day count basis in the terms first.
Dial four: the compounding rest
A "rest" is the moment the bank adds earned interest back to your principal.
For cumulative rupee term deposits, Indian banks compound at quarterly rests. Bank of Baroda, RBL Bank and State Bank of India all describe this convention in their published deposit terms. It follows Reserve Bank of India directives on term deposits.
Quarterly rests mean four compounding events a year. Not twelve. This is worth internalising, because it kills a common misunderstanding.
Some depositors assume a monthly payout option means monthly compounding. It does not. Kotak Mahindra Bank's terms state that monthly interest is paid at a discounted rate, in line with Reserve Bank directives.
The discount exists precisely so that paying you earlier does not hand you extra yield. The bank is neutralising the timing advantage, not gifting it.
There is a second wrinkle. State Bank of India's terms describe compounding on completed quarters, with the leftover days treated separately as a broken period. Those tail days earn simple interest on a 365 day basis.
So a deposit of thirteen months does not compound for thirteen months. It compounds for four quarters, then runs simple for the remainder.
Dial five: the payout mode
Your payout choice does not change how hard your money works. It changes who holds the interest.
Auto renewal deserves care. It rolls your money into whatever rate is current on the maturity date. That rate may sit well below your original one.
We covered the traps in our guide to auto renewal on NRI FDs.
Where the formula breaks: premature withdrawal
Break a deposit early and the bank does not simply pay you less interest. It recalculates the whole thing from scratch.
ICICI Bank's NRI deposit terms describe the mechanism clearly. Interest is paid only for the period the deposit actually ran.
The rate used is the one that applied to that shorter tenure on the booking date. Not your contracted rate.
Kotak Mahindra Bank frames it as the lower of two rates. The rate applicable on the booking date for the actual run period, or the contracted rate, whichever is lower. A penalty is then deducted from that.
There is a harsher clause that catches people out. ICICI Bank states that excess interest already paid to you, through monthly or quarterly payouts, is recovered from the principal.
So a broken deposit can return less than you deposited, in interest terms. The payouts you already spent get clawed back.
NRE deposits carry an additional rule. Bank of Baroda, RBL Bank and Bank of Maharashtra all publish it.
No interest is payable if an NRE deposit closes before one year. Not reduced interest, but none at all.
👉 Tip: Might you need the money inside a year? An NRE deposit is then the wrong instrument. Match the tenure to the need.
Where tax enters the number
The calculation gives you a gross figure. What lands in your account is a net one.
For resident depositors, tax is deducted at source when annual interest crosses a threshold. The threshold and the deduction rate are set by the Income Tax Department, and both have moved recently.
A structural change happened on 1 April 2026.
The Income-tax Act, 2025 replaced the 1961 Act. Reporting from tax practitioners indicates that TDS provisions were consolidated into Section 393.
The same reporting indicates that Form 15G and Form 15H were replaced by a single unified Form 121. Old declarations do not carry forward automatically. Confirm the current position on the Income Tax portal before you file anything.
For NRIs, the rules differ by account type.
The NRO position surprises people. There is no threshold below which deduction is skipped. It applies from the first rupee of interest.
Where a Double Taxation Avoidance Agreement offers a lower rate, you need documentation to claim it. A tax residency certificate and the relevant declaration form are the usual requirements. Our guides on tax on fixed deposits for NRIs and tax on NRE versus NRO accounts go deeper.
If more was deducted than you owed, it does not vanish. You claim it back by filing a return. Our guide to claiming excess TDS deducted by banks sets out the steps.
One more point that is easy to miss. Exemption in India is not exemption everywhere. NRE interest that is tax free here may still be reportable and taxable where you live.
If you are an NRI
Your calculation question is really three questions.
Which account type suits the money. How the currency choice changes the day count. And whether the interest is repatriable when you need it back.
NRE deposits are rupee denominated. You get Indian rupee rates, full repatriability, and exemption from Indian tax while non-resident. You also carry the full currency risk if your spending is in dirhams or dollars.
FCNR deposits hold the money in foreign currency. No currency conversion risk on the principal. Interest is calculated on a 360 day year, per Bank of Baroda's published terms.
NRO deposits handle India sourced income like rent or dividends. Interest is taxable, deduction happens at source, and repatriation is subject to annual limits and certification.
Our comparison of GIFT City FDs against NRE and FCNR deposits sets the three side by side. For the underlying mechanics, see our note on interest calculation on NRI accounts.
If you are a resident Indian
Your domestic FD runs on the quarterly rest convention described above. Nothing exotic there.
What is newer is the GIFT City route. Residents can hold foreign currency deposits there, subject to the Liberalised Remittance Scheme and the unit's own conditions. That gives you USD exposure without an overseas account.
The calculation logic shifts when you do. You move from a 365 day rupee world to a 360 day USD world. You also move outside domestic deposit insurance.
If your entire savings base sits in rupee deposits, that concentration is worth examining. Deposits are not the only route to dollar exposure. GIFT City mutual funds and the wider mutual funds product offer market linked alternatives with a different risk profile.
Worth browsing if you are mapping the space:
These are different instruments with different risks. A deposit gives you a contractual rate. A fund does not.
The GIFT City deposit: a different denominator
GIFT City banking units sit under the International Financial Services Centres Authority. They are not regulated by the Reserve Bank of India in the domestic sense.
That changes three things in the calculation.
The day count basis for USD deposits is 360 days, per ICICI Bank's GIFT City terms. The currency is foreign, so your rupee outcome depends on the exchange rate at exit. And deposit insurance does not apply.
That last point is not a detail. ICICI Bank's GIFT City FAQ states plainly that banking unit deposits are not covered by deposit insurance. Domestic deposits carry insurance up to a set limit per depositor per bank.
We wrote about this specific gap in our guide to GIFT City deposits and insurance. Read it before you size a position.
For the broader picture on how these deposits work, see our overview of NRI fixed deposits in GIFT City.
What we see go wrong
Four patterns recur in our advisory conversations.
Comparing headline rates across currencies.
A USD rate and a rupee rate are not comparable numbers. Different day counts, different inflation, different currency risk.
Assuming monthly payout means monthly compounding.
It does not, and the discounted rate exists to make sure of it.
Booking a long NRE deposit with short term money.
Breaking it inside a year returns zero interest. That is a total loss of yield, not a haircut.
Forgetting the maturity date.
Auto renewal at a lower prevailing rate quietly resets your return for another full term.
Decision clarity
If your goal is a predictable rupee corpus and you are non-resident, the route is simple. An NRE cumulative deposit with quarterly rests fits.
If your goal is dollar preservation without currency conversion risk, FCNR or a GIFT City USD deposit fits better. Check the day count basis and accept the absence of deposit insurance.
If your timeline is under a year, avoid NRE deposits entirely. Use an NRO or a short domestic deposit where partial interest is still payable.
If you live in India and hold only rupee deposits, look at diversification before rates. A better rate on a concentrated position is still a concentrated position.
What happens if you ignore all this
You accept a rate you did not verify. On a day count you did not check. With a compounding frequency you only assumed.
Then you break the deposit early, lose the contracted rate, pay a penalty, and have earlier payouts clawed back. The maturity number in your head was never the number the bank was going to pay.
None of that is a scam. It is arithmetic you did not look at.
Frequently asked questions
Does a higher headline rate always mean a higher maturity amount?
No. Compounding frequency, day count basis and payout mode all affect the final figure. A deposit with a slightly lower rate but a more favourable structure can pay more.
How often do Indian banks compound fixed deposit interest?
Cumulative rupee term deposits compound at quarterly rests, following Reserve Bank of India directives. Deposits below roughly six months are typically calculated as simple interest instead.
Why is FCNR interest calculated on a 360 day year?
It follows the convention the Reserve Bank of India prescribes for foreign currency deposits. Bank of Baroda's published terms confirm the 360 day basis. GIFT City units apply the same basis to several currencies.
Can I avoid tax deduction on my NRO deposit interest?
You cannot avoid it, but you may reduce it. A lower deduction certificate or a treaty rate under a Double Taxation Avoidance Agreement may apply, with proper documentation.
What happens to my deposit rate if I return to India permanently?
Your residential status changes, which changes the account type you are allowed to hold. NRE deposits generally need to be redesignated, and the tax treatment shifts.
Where this leaves you
Fixed deposits look like the simplest product on the shelf. The calculation underneath is not simple. The assumptions people carry into it go wrong in the same few ways.
Before your next deposit, check three things.
The day count basis in the terms. The compounding rest. And what happens if you break it early.
To compare live rates across banks, start with our NRI FD rates explorer. A remembered rate card is not a live one. If you also track Indian market direction, the GIFT Nifty tracker is there.
Looking beyond deposits? Our notes on the GIFT City IPO route and the IPO product cover a different risk profile.
Deposits give certainty. Equity does not.
Questions on your own situation are best asked in our WhatsApp community. Our team and other investors work through these calculations together.
Sources
Reserve Bank of India, directives on interest rates on deposits. This includes the second amendment directions issued on 30 July 2026, effective 1 October 2026.
Bank of Baroda published deposit terms. Covers quarterly compounding, short tenure day count, the FCNR 360 day basis and NRE premature closure.
State Bank of India deposit rate terms on quarterly compounding of completed quarters and 365 day treatment of broken periods.
Kotak Mahindra Bank NRE fixed deposit fees and charges page. Covers simple interest below 181 days, discounted monthly payouts and premature withdrawal.
ICICI Bank NRI fixed deposit interest rate terms on premature withdrawal recalculation and recovery of excess interest paid.
ICICI Bank GIFT City banking unit foreign currency deposit terms. Covers the currency wise day count basis and deposit start dates.
ICICI Bank GIFT City frequently asked questions on the absence of deposit insurance for banking unit deposits.
RBL Bank interest rates page on quarterly compounding and minimum NRE tenure. Bank of Maharashtra NRE deposits page on premature closure before one year.
Income Tax Department portal for current thresholds, deduction rates and forms under the Income-tax Act, 2025.
Rates, thresholds and forms change. Verify current figures directly with your bank and with the relevant regulator before acting.
The stories here are illustrative composites drawn from common patterns, not specific individuals.
This article is for information only and is not personal investment advice. Speak to a qualified advisor about your own circumstances.
