The short answer (then the proof)
Reduce the tenure. Almost always. Keeping your EMI the same and finishing the loan early attacks the interest directly. Reducing the EMI while keeping the tenure just makes the loan slightly cheaper to carry — most of the interest bill survives.
Here's the proof — a PKR 10,000,000 home loan at 20% over 20 years (EMI: PKR 169,882.46; total interest over 20 years: PKR 30,771,790.58). Prepay PKR 1,000,000 in month 13:
Same 1,000,000 prepayment. Tenure reduction saves 15.9 million and kills the loan 99 months (8+ years) early. EMI reduction saves 2.9 million. The tenure option saves over 5x more. (All figures computed from the standard EMI formula; rounded to the rupee.)
Why? Interest is charged on the outstanding balance every month. Tenure reduction wipes out the tail of the loan — the months where you'd otherwise keep paying interest on a still-large balance. EMI reduction spreads the benefit thinly across all remaining months. Concentrated beats diluted, every time.
- No prepayment: loan ends month 240 — total interest 30,771,791, interest saved —
- Reduce tenure: EMI stays 169,882, loan ends month 141 — total interest 14,866,206, interest saved 15,905,584
- Reduce EMI: EMI drops to 152,815, loan ends month 240 — total interest 27,897,539, interest saved 2,874,251
Why timing is everything: year 1 vs year 10
The same prepayment, made late, is worth a fraction. Take that same PKR 1,000,000 — but prepaid in month 121 (year 10) instead of month 13, with tenure reduction:
The late prepayment saves barely a quarter of the early one. The reason is in your amortization schedule: early payments are almost all interest, so killing principal early destroys future interest. By year 10, you've already paid most of the loan's interest — there's less left to save. Rule: prepay as early as the loan allows. Every year you wait, the prize shrinks.
- Prepaid in year 1: saves 15,905,584 in interest, 99 months cut
- Prepaid in year 10: saves 4,461,758 in interest, 32 months cut
The 12+1 habit: one extra EMI per year
Can't find a lump sum? The quietest wealth-builder in borrowing: pay one extra EMI per year — from a bonus, tax refund, or just dividing one EMI by 12 and adding it monthly. On that same 10,000,000 / 20% / 20-year loan:
No windfall needed — just one extra payment a year, and you erase nearly 14 million in interest. Automate it if your bank allows; if not, calendar it with your annual bonus.
- Normal: 240 months, 30,771,791 total interest
- One extra EMI per year: 148 months, 17,033,172 total interest
- Saved: 13,738,619 in interest, 92 months (7.7 years) cut
Lump sum vs drip: one big prepayment or several small ones?
What if you can't do 1,000,000 at once — is four 250,000 prepayments (one per year) nearly as good? Computed on the same 10,000,000 / 20% / 20-year loan, all with tenure reduction:
The single early lump wins by about 2.2 million. The lesson: earliness beats size. Money prepaid in month 13 kills ~19 years of interest on that principal; money prepaid in month 49 kills ~16. So if you're choosing between "wait until I have the full amount" and "prepay what I have now" — prepay now. Don't let the perfect lump sum be the enemy of the good partial one.
- PKR 1,000,000 once, in month 13: saves 15,905,584, loan ends month 141
- PKR 250,000 yearly in months 13/25/37/49: saves 13,703,814, loan ends month 154
How to actually make a prepayment (the practical steps)
The math is the easy part. Here's the paperwork:
- Read your loan agreement's prepayment clause first. Note the lock-in period (if any), the penalty percentage, and whether partial prepayments are allowed or only full settlement.
- Give written instruction to the bank — in person or through their app/portal — stating the amount and explicitly choosing "reduce tenure" (or "reduce EMI" if cash flow is the goal). Don't assume the default; banks often default to EMI reduction because it keeps you paying longer.
- Get the revised amortization schedule in writing after the prepayment is applied. Verify the new tenure/EMI and that the prepayment was applied to principal, not parked as an "advance EMI."
- Keep proof — the instruction copy, the bank's acknowledgment, and the before/after schedules. If a dispute arises years later, this paper trail is everything.
- Confirm the penalty (if any) was charged correctly — and that no penalty was charged during a penalty-free window.
Step-by-step: compute your own prepayment scenario
Since our free EMI calculator at https://all-done.xyz/tools/emi-calculator covers the base loan math (EMI, totals, full schedule) but doesn't model prepayments, here's the exact method for your own numbers:
One honest caveat: this method assumes a fixed rate. If your loan has a floating rate, a rate hike after your prepayment changes the numbers — prepaying before an expected hike is worth more, not less, because it shrinks the balance the higher rate applies to.
- Run your loan through the calculator and open the amortization schedule. Find your balance at the prepayment month.
- Subtract the lump sum from that balance — that's your new principal.
- Tenure reduction: keep the same EMI; the remaining term is however many months it takes the EMI to amortize the new principal (your bank's revised schedule will show it; the interest saved is the difference in total interest).
- EMI reduction: keep the remaining term; recompute the EMI on the new principal over the remaining months (EMI = P' × r × (1+r)ⁿ' / ((1+r)ⁿ' − 1)).
It's not just home loans: car and personal loan examples
The math is universal. A personal loan — PKR 1,500,000 at 26% over 4 years (EMI: 50,575.96; total interest: 927,646). Prepay PKR 300,000 in month 7:
Even on a short 4-year loan, tenure reduction saves 2.2x more. And because personal-loan rates are the highest you'll pay, every rupee of early principal is your best "investment" — a guaranteed 26% return, risk-free. No mutual fund promises that.
- Tenure reduction: loan ends at month 36 (12 months early), saves 336,072 in interest
- EMI reduction: EMI drops to 39,459.88, saves 155,759 in interest
When NOT to prepay
Prepayment isn't always the right move. Don't prepay when:
- You have no emergency fund. 3–6 months of expenses in liquid savings comes before prepayment. A prepaid loan can't pay a hospital bill.
- The money earns more elsewhere, safely. If your loan is at 18% and the alternative is a savings account at 12%, prepay. (Be honest about "safely" — speculative returns don't count.)
- There's a heavy prepayment penalty. Some loans charge 2–5% on prepaid amounts or lock you out entirely in the first year. Compute the penalty against the interest saved — sometimes waiting a year is the winning move. Always read the prepayment clause before you need it.
- You'd be left cash-strapped. Draining every rupee to kill a loan, then borrowing at higher rates for the next emergency, is going backwards.
The only case for reducing EMI
Reduce the EMI instead of the tenure when monthly cash flow is the emergency — a job loss, a pay cut, a new unavoidable expense. The EMI reduction in our example freed up ~17,000/month. That's real breathing room. But treat it as what it is: buying cash-flow relief at the price of ~13 million in extra interest versus the tenure option. The moment cash flow stabilizes, switch back to tenure reduction (most lenders let you choose per prepayment).
How to run the numbers yourself
Our free EMI calculator at https://all-done.xyz/tools/emi-calculator gives you the base loan math — EMI, total interest, total payable, and the full month-by-month amortization schedule — instantly in your browser. A note on honesty: it doesn't model prepayments, so for the prepayment scenarios above, use the method in this guide: compute your balance at the prepayment month from the schedule, subtract the lump sum, then recompute the remaining term at the same EMI (tenure reduction) or the new EMI over the remaining term (EMI reduction). (Tip: the currency box accepts any text — type PKR.)
