Extra mortgage payments:
see the years and interest you can cut

What an extra payment actually does

When you pay more than the EMI, the extra goes straight to principal. A smaller balance means less interest next month, which means more of your regular EMI goes to principal too. The effect snowballs, and it is strongest early in the loan when the balance is high.

Two things can change as a result: the remaining tenure or the EMI. Most borrowers who can afford it keep the EMI unchanged and shorten the tenure, because that saves the most interest. This guide assumes that approach unless stated otherwise.

Look at month one. Interest is 40,00,000 × 8.5% ÷ 12 = ₹28,333, so only about ₹6,380 of the ₹34,713 EMI repays principal. A ₹5,000 extra payment lifts the principal repaid that month to about ₹11,380, which is 78% more than the schedule planned.

The calculator on this page works from your amount, rate and tenure. The numbers below use ₹40,00,000 at an assumed 8.5% for 20 years, with the normal EMI of about ₹34,713. Your rate and balance will differ.

How to calculate the effect of extra payments

1. 1Work out the regular EMI for the original loan.
2. 2Run the schedule month by month with the extra amount added to the payment.
3. 3Count the months until the balance reaches zero.
4. 4Compare total interest with the original schedule: the gap is your saving.

Timing inside the month matters a little. Some lenders recalculate interest daily on the outstanding balance, others monthly on the opening balance, so the same payment can save slightly different amounts. Ask when your extra payment is credited and from which date the lower balance is used.

Doing this by hand takes 178 rows for the ₹5,000 case below, which is why a calculator is the practical tool. It is still worth understanding the loop, because it shows you why early extra payments are worth much more than late ones.

Worked example: ₹5,000 more every month

Notice what the schedule is doing. The EMI is unchanged at ₹34,713, but the loan is retired after 14 years 10 months instead of 20 years. The last instalment is smaller than a full EMI because only the leftover balance is due.

You are paying ₹60,000 more a year, and over 14 years and 10 months that is about ₹8.9 lakh of extra money. In return you avoid roughly ₹13 lakh of interest and are debt-free more than five years sooner.

How much extra is worth it?

Savings are not proportional to the extra amount. Going from ₹2,000 to ₹5,000 more than doubles the saving, because the extra money is working on a larger balance for longer. Even ₹1,000 a month shortens the loan by 16 months and saves roughly ₹3.5 lakh.

If a fixed monthly extra feels heavy, many borrowers pay one additional EMI each year, often when a bonus arrives. On the same loan, one extra EMI of ₹34,713 every twelve months ends the loan after about 201 months (16 years 9 months), which is 39 months early, and saves about ₹8.2 lakh of interest.

That works out to roughly ₹2,893 a month in extra outgo, so it sits between the ₹2,000 and ₹5,000 rows above. It is a good fit for people with irregular income, because the amount flexes with the year instead of locking in a larger monthly commitment.

Lump sum or monthly extra, and when to pay

The same logic applies to bonuses and windfalls. A one-time payment of ₹2,00,000 is far more valuable early than late, because it removes interest for more months. Remember that money prepaid cannot easily be taken back from the lender, so keep your emergency fund outside the loan.

If you ask the lender to lower the EMI instead of shortening the tenure, you give up much of that saving. In the ₹2,00,000 lump-sum case paid after one year, a lower EMI of about ₹32,942 over the remaining 228 months saves about ₹4.04 lakh of interest, against ₹7.13 lakh when the EMI stays at ₹34,713.

Prepay or invest: compare rates, not feelings

Every rupee you prepay earns a certain return equal to your loan rate, because it stops interest at that rate. Prepaying ₹1,00,000 on an 8.5% loan saves about ₹8,500 of interest in the first year on that amount.

Set that against the best alternative after tax. Assume a fixed deposit pays 7% and your interest is taxed at 30%: the after-tax return is 7% × (1 − 0.30) = 4.9%, well below the 8.5% you save by prepaying. These are assumptions to show the method, not current rates.

Investments with higher expected returns may beat the loan rate, but the return is not guaranteed and can be negative in some years. A common compromise is to hold an emergency fund, put long-term goals into investments, and direct a fixed share of every bonus into the loan.

Before you prepay: mistakes and trade-offs

• Prepaying while holding a higher-cost debt such as a credit card balance. Clear that first.
• Draining your emergency fund. Keep several months of expenses accessible before prepaying.
• Ignoring tax effects. Interest and principal deductions can change what a prepayment really saves, so check the current rules.
• Skipping the lender's rules. Some loans charge a fee, and some apply the extra to the next EMI instead of the principal.
• Assuming the saving is guaranteed. A rate change on a floating loan alters the whole schedule.

Prepayment is not always the best use of spare money. Compare the interest rate on your loan with what you could realistically earn, after tax and risk, elsewhere. A guaranteed saving at 8.5% is hard to beat with low-risk alternatives, but it also removes flexibility you cannot get back.