Calculate interest saved and tenure reduction from a lump sum prepayment on your existing loan.
Actual savings depend on bank's prepayment policy and any foreclosure charges (typically 2–5%).
Prepay in the first 5–7 years when interest component is highest. Use bonus or windfall income. Compare prepayment vs investing at higher return — if loan rate 8.5% < investment return 12%, consider investing instead.
If loan rate is 8.5% and you can earn 12%+ in equity, invest. If loan rate is 10%+, prepaying is better. For peace of mind, prepaying is always valid.