Three rules before the next EMI hits.
The math is the easy part. The rest is structuring the comparison honestly and pricing the bits that do not show up on a spreadsheet.
01
Compare post tax to post tax.
Brochure rate against brochure return is the wrong frame. Strip the loan rate by Section 24 status. Strip the equity number by LTCG. The right gap is between those two stripped numbers, not the headline pair.
02
Charge a risk premium for certainty.
Loan rate is contractual. Equity is expected. Demand 2 to 3 percentage points of margin before paying for fifteen years of variance. If the post tax gap is under four points, the equity premium is not paying for the variance you are taking.
03
Price the behavioural leak.
The EMI you "would have invested" rarely lands in the SIP every month for fifteen years. Prepayment locks the alpha in. Investing rents it back from your future self every thirty days.
Closer
The math says invest. The behaviour says prepay. Both can be true, and your ITR decides which.