Home Loan Prepayment vs Investing: What I Do With Extra Money Every Year

Every time I get a bonus or a windfall, I face the same question: prepay part of the home loan or put it in my SIP? After doing this analysis a few times, here's the framework I use — and the answer isn't always what people expect.

The Core Math

A home loan at 8.5% interest is costing you 8.5% guaranteed, post-tax. An equity SIP earns an uncertain 10–12% pre-tax over the long run.

The comparison isn't 8.5% vs 12%. It's after-tax cost of loan vs after-tax return on investment.

After-tax cost of home loan:

• Interest rate: 8.5%
• 80EEA/24(b) tax benefit on interest (old regime): up to ₹2L deduction per year
• If you're in 30% bracket: effective interest cost = 8.5% × (1 − 0.30) = 5.95%
• If deduction is fully utilized, your real borrowing cost is ~6%

After-tax equity return:

• Expected return: 12% CAGR
• LTCG tax at 12.5% on gains above ₹1.25L
• Effective after-tax return: roughly 10–10.5%

On pure math: Invest — 10.5% beats 6% comfortably.

When Prepayment Wins

1. You're in the new tax regime: Under the new tax regime, home loan interest deduction (24b) is not available. Your effective loan cost is the full 8.5% — unshielded by tax. Now the math is closer: 8.5% guaranteed cost vs 10.5% uncertain return.

For risk-averse people, the guaranteed 8.5% savings from prepayment starts to look attractive.

2. Your loan is in the second half of its tenure: Home loan EMIs are front-loaded with interest — in early years, 80%+ of your EMI is interest. By year 12 of a 20-year loan, you're paying more principal than interest. Prepaying at this stage saves less interest per rupee than prepaying in year 2.

Prepayment is most effective in years 1–7 of a home loan.

3. You're near retirement: Carrying debt into retirement is psychologically and financially risky. If you're within 5 years of retiring, aggressively prepay even at the cost of lower investment returns — the peace of mind and cash flow certainty is worth it.

4. Your EMI-to-income ratio is high: If EMI is above 40% of take-home salary, reducing it via prepayment gives you cash flow relief that makes other financial goals more achievable.

When Investing Wins

1. You're in the old tax regime and maximizing 24(b): Your effective loan cost is ~6%. Long-term equity returns of 10–12% make investing clearly superior.

2. Your loan rate is below 8%: Some people refinanced at 6.5–7% during 2020–21. At those rates, investing in equity beats prepayment even without tax benefits.

3. You haven't maxed your equity allocation: If your equity SIP is below 15–20% of income, build that habit first. The compounding benefit of starting equity investment early outweighs the marginal interest saved on prepayment.

4. You have no emergency fund: Never use a bonus to prepay a loan if you don't have 6 months of expenses liquid. The loan is a known liability. A job loss without an emergency fund is an unknown catastrophe.

The Practical Hybrid Approach

I split extras: 60% to investments, 40% to prepayment — adjusted based on loan vintage and tax regime.

Why not 100% one way?

• Full prepayment removes your 24(b) benefit once the loan is closed
• Full investment means carrying debt for 20 years when you could have cleared it in 14
• The hybrid gives you psychological progress on debt reduction AND wealth compounding

Every 3–4 years, check your remaining loan tenure. If prepayments have reduced it significantly, re-evaluate.

How to Prepay Effectively

• Reduce tenure, not EMI: When you prepay, always ask the bank to reduce tenure, not EMI. Keeping EMI the same and reducing tenure saves far more interest overall.
• Check for prepayment charges: Most floating rate loans have zero prepayment penalty. Fixed rate loans may charge 2%. Verify before prepaying.
• Use annual partial prepayments: A lump sum annual prepayment is more effective than spreading the same amount across 12 months because it reduces the outstanding principal on which future interest is calculated.

The One Number to Calculate

Take your current effective home loan interest rate (after accounting for tax benefits in your regime). Compare it to your expected after-tax investment return based on your asset allocation. If the difference is less than 2%, follow your risk tolerance. If the difference is more than 3%, follow the math.

For most salaried Indians under old regime with equity-heavy portfolios: invest first, prepay with what's left.