This is the most common dinner-table finance debate in India. You have a home loan at, say, 9%. You also believe equity SIPs return 12% over the long run. So obviously the SIP wins, right? Not so fast.
The simple version (ignore for now)
Net of taxes:
- Home loan interest paid: 9% (and some of it is tax-deductible under Section 24, lowering effective cost to ~6.3% for a 30% slab)
- Equity SIP return: 12% (with 10% LTCG above ₹1L gain → effective ~10.8%)
So after tax: equity ~10.8% vs loan ~6.3%. Equity wins by ~4.5 percentage points. Run it for 20 years and you're meaningfully ahead.
But this analysis is incomplete. Three things change the answer.
What the simple version misses
1. Risk-adjusted return, not nominal
Prepayment is guaranteed. You save exactly the interest you would have paid. Equity is expected — actual returns might be 6%, 14%, or anything in between. The certainty premium is real.
For risk-averse investors (the majority of people who get into this debate), prepayment is psychologically much easier. If the equity SIP underperforms for 3 years running, you'll likely panic and quit at exactly the wrong moment.
2. The Section 24 cap
Home-loan interest deduction is capped at ₹2 lakh per year for self-occupied. Beyond that cap, the deduction is zero, so the effective cost of those marginal rupees of interest is the full 9%, not the post-tax 6.3%. Prepaying the capped portion is much better math.
3. Tenure dynamics
The compelling case for SIP is at the start of a long horizon. The compelling case for prepayment is at the start of a loan tenure (where interest dominates). Both compete for the same "early" rupees.
The decision framework
| Your situation | Tilt towards |
|---|---|
| Loan rate < 8.5% | SIP (math favors equity) |
| Loan rate > 10% | Prepay (guaranteed return is hard to beat) |
| You've already exhausted ₹2L Section 24 deduction | Prepay the excess |
| You're emotionally rattled by market drops | Prepay (don't risk the panic-quit) |
| You have 15+ years on the loan and 15+ years until retirement | Split — do both, 60/40 in favor of SIP |
| You're close to retirement (< 7 years) | Prepay (de-risk the cashflow) |
The "split" answer is usually correct
Most people don't have to choose 100/0. Split your surplus ₹50k as ₹30k SIP + ₹20k prepayment. You get:
- Some upside from equity
- A shrinking loan tenure
- Behavioral comfort that ratchets up over time
- Tax-efficient utilization of the ₹2L Section 24 cap
A specific rule that works for most middle-income earners: keep your prepayment exactly equal to your annual loan-interest excess over ₹2L (the un-deductible portion), and SIP the rest.
Calculators that help
- EMI Calculator — see how prepayment changes tenure and interest
- SIP Calculator — project the equity side
- Coming soon: a unified split-optimizer that takes your loan + surplus + tax slab and recommends the best split
For now, run both numbers, weigh your risk appetite, and pick the answer you can sleep with.
