Take out a ₹50,00,000 home loan at 8.5% for 20 years and your monthly payment is about ₹43,400. The surprise comes when you look at the first year's statement: of that ₹43,400, roughly ₹35,400 is interest and only ₹8,000 pays down the principal. That front-loaded interest is amortization — and once you see it clearly, the case for (and against) extra payments becomes obvious.
How amortization works
Every month, your payment is split in two. The interest portion is the outstanding balance times the monthly rate; the rest reduces the balance. Because the balance starts at its maximum, so does the interest — and because the balance shrinks slowly at first, the principal reduction starts tiny. Over 20 years, the split slowly inverts from mostly-interest to mostly-principal. The loan doesn't get cheaper over time; the interest just gets smaller as the balance falls.
What a lump-sum prepayment does
A prepayment reduces the principal, which immediately cuts the interest charged on every future payment. That's the same as shortening the loan: keep paying the same EMI and the loan ends years earlier. On the ₹50,00,000 loan above, a one-time ₹5,00,000 prepayment in year one cuts the total interest by roughly ₹11–12 lakh and shortens the term by about 2.5 years. The earlier the prepayment, the bigger the effect — because you're removing principal that would otherwise have generated interest for the remaining term.
Check the fees before prepaying
Many Indian lenders charge a prepayment penalty on floating-rate home loans (usually waived) and on fixed-rate loans (often 2–4% of the amount). Calculate the penalty against the interest saved before deciding — a ₹50,000 penalty can erase a year of savings.
When extra payments DON'T help
- When the loan is near the end — most of the remaining payments are principal, so prepaying saves little interest.
- When the rate is low and you have higher-interest debt — paying off a 14% credit card beats prepaying an 8.5% mortgage.
- When it drains your emergency fund — liquidity matters more than a slightly shorter loan.
- When your tax situation rewards the interest — home-loan interest can be deductible, so run the after-tax comparison.
Model your own loan
ForgePlug's Mortgage Calculator shows the full amortization schedule and a what-if extra-payment comparison, so you can see the interest you'd actually save.
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