Every once in a while, money shows up that you were not planning for. A bonus. A tax refund. A client who finally paid. Maybe you sold something. Or you just saved more than usual that month.

Most people spend it. Some people park it in a savings account earning 3 to 4 percent interest per year. And then there is the third option and putting it towards your loan is which most people either do not think about or assume is complicated.

It is not complicated. And the difference it makes is bigger than most people expect.

What Actually Happens When You Make a Part Payment

When you pay your regular EMI every month, the money is split between interest and principal. In the early months of a loan, most of your EMI goes towards interest. Very little actually reduces what you owe.

A part payment works differently. The entire amount you pay goes directly towards reducing your outstanding principal. No portion of it goes to interest. That one fact is what makes it so powerful.

When your principal drops, the interest calculated next month is lower. Which means more of your next EMI goes towards principal. Which lowers it further. The effect compounds quietly, month after month, for the rest of the loan.

The Two Choices You Get

When you make a part payment, most banks give you two options. You can either keep your EMI the same and reduce the total number of months left on your loan, or keep the tenure the same and get a lower EMI going forward.

Reducing the tenure saves you more money overall. Reducing the EMI improves your monthly cash flow. Both are valid depending on your situation, but if the goal is to pay the least possible interest, reducing tenure wins every time.

Real Numbers So This Actually Makes Sense

The Setup

Loan amount: Rs. 10,00,000

Interest rate: 10.5% per year

Tenure: 5 years (60 months)

Monthly EMI: Rs. 21,491

Total interest without any part payment: Rs. 2,89,460

Now say at the end of month 12, you receive a bonus of Rs. 1,00,000 and you put the entire amount as a part payment towards your loan.

What Changes

Outstanding before part payment: Rs. 8,34,272

Outstanding after part payment: Rs. 7,34,272

If you choose to reduce tenure:

Remaining months drop from 48 to 38

Total interest paid now: Rs. 2,25,140

You save Rs. 64,320

And you get out of debt 10 months earlier.

One payment. One decision. You saved over 64,000 rupees in interest and finished your loan almost a year ahead of schedule.

That same Rs. 1,00,000 in a savings account at 4% would have earned you around Rs. 4,000 over that same period. The math is not close.

The Earlier You Pay, the More You Save

This is the part most people miss. Making a part payment in month 6 saves you significantly more than making the same payment in month 40. The reason is simple. The earlier you reduce the principal, the more months there are left for that reduction to have an effect on your interest calculation.

If your loan has 10 months left, making a part payment of Rs. 50,000 will save you a relatively small amount. If your loan has 48 months left, that same Rs. 50,000 works for 48 months compounding your savings every single month.

The golden window for part payments is roughly the first half of your loan tenure. If your loan is 5 years, the first 2.5 years is when part payments have the highest impact. After that the savings reduce, but they are still worth making.

What About Prepayment Charges

Some loans charge a fee if you pay ahead of schedule. For floating rate loans, RBI guidelines prohibit banks from charging prepayment penalties on individual borrowers. So if you have a home loan at a floating rate, you can make part payments without any penalty.

For fixed rate loans and personal loans, some lenders do charge a prepayment fee, typically 2 to 4 percent of the amount being prepaid. Before you make a part payment, check your loan agreement or call your bank to confirm if a penalty applies. In most cases, even with a 2 percent fee, the savings from reducing the principal still outweigh the cost.

Multiple Part Payments Work Even Better

You do not have to wait for a large windfall. Multiple smaller part payments throughout the loan work just as well, sometimes better. Rs. 20,000 paid in month 6, another Rs. 30,000 in month 14, and Rs. 50,000 in month 24 can save you more than a single Rs. 1,00,000 payment made in month 20.

The key is to make the payment as early as you can, with whatever amount you have available at that point. Do not wait to accumulate a big round number if you have money sitting idle now.

Not sure when to make a part payment and when it might not make sense? Read the next article on exactly that.