How prepayment saves interest
Interest on a home loan or personal loan is charged every month on the outstanding balance. When you prepay, the whole amount goes towards principal, so the balance drops immediately and every future month's interest is calculated on a smaller amount. You are not just saving interest on the prepaid sum for one month — you avoid interest on it for every month that would otherwise have been left on the loan.
That is why the timing matters so much. In the early years of a long loan most of each EMI is interest, and the balance falls slowly. Prepaying then removes principal that would have been charged interest for many years.
Reduce EMI or reduce tenure?
When you prepay, many lenders let you choose what happens next:
Option A: Reduce tenure, keep the EMI
Your EMI stays the same and the loan simply ends earlier. Because you keep paying the full EMI on a smaller balance, more of each instalment goes to principal, and the balance falls faster month after month. This option saves the most interest.
Option B: Reduce EMI, keep the tenure
The lender recalculates your EMI on the reduced balance over the months still left. Your monthly outgo falls, but you keep paying for the original number of months, so the interest saving is smaller. This suits you if you want lower EMIs — for example, to free up cash for other goals or to build a buffer against a drop in income.
If you are unsure, a middle path is to reduce tenure and keep a healthy emergency fund. You can always ask your lender later to reduce the EMI if your circumstances change, subject to their policy.
How this calculator works
First it works out the EMI that repays your outstanding balance over the remaining tenure:
EMI = P × r × (1 + r)n ÷ [(1 + r)n − 1]
P is the outstanding principal, r is the monthly rate (annual rate ÷ 12 ÷ 100) and n is the number of months left. It then simulates the loan month by month, twice — once without prepayment and once with it:
- Interest for the month = balance × r.
- Principal repaid = EMI − interest. The final EMI is trimmed so the balance ends at exactly zero.
- Any extra monthly payment is then taken off the balance.
- In a prepayment month (and on every anniversary of it, if you choose “Every year”), the lump sum is taken off the balance. A prepayment larger than the balance simply closes the loan.
- Reduce tenure: the EMI never changes. Reduce EMI: after each lump sum, the EMI is recalculated on the new balance over the months left in the original tenure. Extra monthly payments never change the EMI; they always shorten the loan.
Interest saved = total interest without prepayment − total interest with prepayment. If you enter a prepayment fee, it is charged on each amount prepaid and paid separately, and the net saving is interest saved minus fees.
Worked example: ₹2 lakh prepaid on a ₹30 lakh home loan
You owe ₹30,00,000 at 8.5% with 15 years (180 EMIs) left, and you prepay ₹2,00,000 along with your next EMI.
- Current EMI ≈ ₹29,542. Without prepayment, total interest over the remaining 15 years ≈ ₹23,17,594.
- Month 1: interest = ₹30,00,000 × 8.5% ÷ 12 = ₹21,250, so ₹8,292 of the EMI repays principal. After the ₹2 lakh prepayment the balance is ≈ ₹27,91,708.
| Option | EMI | Loan ends after | Total interest | Interest saved |
|---|---|---|---|---|
| No prepayment | ₹29,542 | 15 years | ₹23,17,594 | — |
| Reduce tenure | ₹29,542 | 13 years 2 months | ₹18,61,766 | ₹4,55,828 |
| Reduce EMI | ₹27,567 | 15 years | ₹21,64,080 | ₹1,53,514 |
Keeping the EMI cuts 22 months off the loan and saves about three times as much interest as lowering the EMI. Lowering the EMI, on the other hand, frees up about ₹1,975 a month for the rest of the loan. If you repeat the ₹2 lakh prepayment every year and keep the EMI, the loan closes in about 7 years 1 month and saves about ₹13.6 lakh in interest.
Savings at different prepayment amounts
Same loan, one prepayment with the next EMI:
| Prepayment | Interest saved (reduce tenure) | Time saved | New EMI (reduce EMI) | Interest saved (reduce EMI) |
|---|---|---|---|---|
| ₹50,000 | ₹1,23,834 | 5 months | ₹29,048 | ₹38,378 |
| ₹1,00,000 | ₹2,40,729 | 11 months | ₹28,555 | ₹76,757 |
| ₹2,00,000 | ₹4,55,828 | 1 year 10 months | ₹27,567 | ₹1,53,514 |
| ₹5,00,000 | ₹9,79,718 | 4 years 2 months | ₹24,605 | ₹3,83,785 |
When prepayment helps most
The same ₹2 lakh prepayment on the loan above saves very different amounts depending on when you make it, if you keep the EMI:
- Now (month 1): about ₹4,55,828 saved, 22 months shorter.
- After 5 years (month 61): about ₹2,40,827 saved, 14 months shorter.
- After 10 years (month 121): about ₹93,820 saved, 9 months shorter.
Prepayment tends to make the most sense when:
- many years are left on the loan, so most of each EMI is still interest;
- your loan rate is high compared with what you can safely earn elsewhere;
- you already have an emergency fund and adequate insurance;
- you get little or no tax benefit from the interest you pay;
- there is no prepayment fee, or the fee is small compared with the interest saved.
To see how your balance splits between principal and interest year by year, use the home loan EMI calculator with amortization schedule. For car, personal or education loans, the EMI calculator shows the same breakdown.
Prepayment charges and RBI rules
The Reserve Bank of India has directed that lenders should not levy foreclosure charges or prepayment penalties on floating-rate term loans to individual borrowers taken for purposes other than business. In practice this means most individuals with a floating-rate home loan can prepay without a penalty.
Fixed-rate loans, loans taken for business purposes and some other products may still carry a prepayment or foreclosure charge, often a percentage of the amount prepaid. Lenders may also set a minimum prepayment amount or limit how often you can prepay. Read your loan agreement or ask your lender before you pay, and enter any fee in the calculator to see your net saving.
Is prepaying better than investing?
Prepaying a loan is like earning a guaranteed return equal to your loan rate: every rupee you prepay stops being charged that interest. There is no market risk and no tax on this “return”. Investing the same money — for example through a SIP in mutual funds — may earn more over long periods, but the return is not guaranteed, can be negative for years at a time, and may be taxed when you withdraw.
To compare the two fairly, look at what the same lump sum is worth at the end of the same period. In the example above, ₹2,00,000 prepaid with the next EMI avoids 8.5% interest (compounded monthly, about 8.84% a year effective) for the remaining 179 months. That is worth the same as ₹2,00,000 growing to about ₹7,07,519. Invested at an assumed 10% a year for the same period, it would grow to about ₹8,28,840 before tax. If tax took 12.5% of the gain, the after-tax value would be about ₹7,50,235, and the investment would need to earn about 9.55% a year just to match prepaying.
A few more points to weigh:
- Tax deductions change the effective loan rate. If you claim home loan interest under the old tax regime, your after-tax borrowing cost is lower than the headline rate, which makes prepaying less attractive.
- Liquidity. Money prepaid into a loan is hard to get back. Money invested can usually be withdrawn, though possibly at a loss.
- Emergency fund first. Keep several months of expenses accessible before prepaying.
- Floating rates move. If your loan rate rises, the guaranteed return from prepaying rises too.
The calculator's “Prepay or invest” section runs this comparison with your own figures. To estimate how regular monthly investments might grow instead, try the SIP calculator. This is an illustration, not personalised advice.
Tax considerations
Under the old tax regime, interest on a home loan for a self-occupied house can be deducted under Section 24(b), and principal repayment can count towards Section 80C, both subject to limits and conditions. Prepaying reduces the interest you pay in future years, so it also reduces the interest deduction you can claim. If your annual interest is already above the deduction limit, prepaying may not reduce your tax benefit at all in the near term. The new tax regime does not allow these deductions for a self-occupied home. Tax rules change, so confirm the current position with a tax professional.
Important assumptions
- The interest rate stays the same for the rest of the loan. Floating rates can change.
- Prepayments are credited with the EMI of the chosen month and reduce principal straight away.
- The calculated EMI repays your balance exactly over the remaining tenure; your lender's figures may differ slightly due to rounding and the date interest is charged.
- Processing charges, insurance and tax benefits are not included.
Planning a new purchase rather than an existing loan? The home loan calculator works out your loan amount, EMI and upfront cash from the property price and down payment.