Prepay Loan or Invest Calculator

Understanding this calculator

You have spare money and a running loan. Repaying early gives a certain, tax-free saving at exactly the loan's rate. Investing might do better, and might not. The calculator compares them properly; this is what sits underneath the comparison.

Prepaying is a guaranteed, untaxed return

Repay ₹1 lakh on an 8.5% loan and you have saved 8.5% a year on that money, with certainty, for the remaining tenure. No market has to cooperate.

And it is untaxed. An 8.5% saving from prepayment is worth 8.5%. An 8.5% return from an investment is taxed before you keep it. That is why the comparison has to be made after tax on the investing side, which is what this calculator does and most comparisons do not.

Comparing certainty with expectation

The two sides of this decision are not the same kind of number. The loan rate is a fact. The investment return is a forecast, and one that arrives as a volatile series rather than a steady line.

So an expected return marginally above the loan rate is not a reason to invest — the expectation carries risk the loan saving does not. A meaningful gap, over a long horizon, is a different proposition. Where that line sits depends on how much uncertainty you are prepared to carry, which is a judgement rather than an arithmetic result.

What this calculator cannot weigh for you

• ▹**Tax deductions on the loan.** Under the old regime, home loan interest and principal repayment may be deductible, which lowers the loan's effective cost and shifts the comparison. Under the new regime they generally are not.
• ▹**Liquidity.** Money paid into a loan is gone. Money invested can be reached in an emergency — and a prepayment that leaves you without an emergency fund can force expensive borrowing later.
• ▹**Timing within the tenure.** Prepaying early saves far more than the same amount prepaid late, because it removes interest that would have accrued over the longest remaining period.
• ▹**How it feels to be debt-free.** Not a number, and not nothing. Plenty of people sleep better having prepaid, and that is a legitimate reason.

The deductions, if you are on the old regime

This is the detail that most often flips the answer, and it applies only under the old tax regime.

Where the interest is deductible, the loan's effective cost is lower than its rate — a 8.5% loan for someone in the 30% band can cost nearer 6% after the deduction, which raises the bar an investment has to clear. Where it is not deductible, the loan costs exactly what it says, and prepaying is correspondingly stronger.

One caveat that cuts the other way: the ₹2 lakh interest cap is an annual ceiling, and on a large loan in its early years the interest often exceeds it. Interest above the cap earns no deduction at all, so the effective-cost argument applies to part of the interest rather than all of it.

A sensible order to decide in

1. 1.**Keep an emergency fund first.** Prepaying to the point where an unexpected expense forces you onto a credit card undoes the entire saving several times over.
2. 2.**Clear expensive debt before cheap debt.** A credit card or personal loan at 14% or more should be repaid before any home loan and before investing — that is a guaranteed return nothing in a market will match.
3. 3.**Then compare the remaining loan against an after-tax expected return**, which is what the calculator above does.
4. 4.**Prepay early in the tenure if you prepay at all.** The same rupee removes far more interest in year three than in year fifteen.