Sinking Fund: Meaning, Formula, and How it Works

A sinking fund is money you set aside regularly for a specific expense that you expect in the future. It helps you spread a large cost across several months or years instead of arranging the full amount at once.

Before starting one, decide the amount you need and the time available to save. You can then divide the target by the number of saving periods to estimate your regular contribution.

The main points to remember are:

• You can create a sinking fund for a car purchase, education, home repairs, insurance premiums or asset replacement.
• A sinking fund is meant for a planned expense, while an emergency fund is meant for unexpected financial needs.
• A Rs. 1,20,000 goal over 24 months requires Rs. 5,000 per month if you do not account for any investment returns.
• A Rs. 10 lakh goal over 5 years requires Rs. 2 lakh per year on a simple saving basis.
• You can keep the money in a suitable savings or investment option based on your goal, timeline and risk.

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A sinking fund is a planned savings pool created for a specific future expense or financial obligation. You contribute money regularly until you have enough to meet the planned expense.

For example, suppose you expect to replace your car in five years. Instead of arranging the full amount when you buy the new car, you can set aside money every month or year towards that goal.

A sinking fund can also be used by companies. A business may set aside money over time to repay debt, replace equipment or meet another large financial obligation.

The key feature is the same in both cases: you prepare for a known future expense by saving towards it in advance.

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The sinking fund method involves setting a target, deciding when you will need the money and making regular contributions towards that target.

For a simple saving plan, you can use this calculation:

Regular contribution = Target amount ÷ Number of saving periods

For example, if you need Rs. 1,20,000 after 2 years and save every month:

Rs. 1,20,000 ÷ 24 months = Rs. 5,000 per month

This calculation does not include any interest or investment returns. If your money earns a return, the amount you need to contribute may differ.

The basic process is:

• Decide how much money you will need.
• Set the date by which you need the money.
• Work out how much you need to save each month or year.
• Keep the money separate from your regular spending.
• Review your progress regularly.

A sinking fund works best when the target and date are clear.

A simple example can show how a sinking fund works in practice.

Suppose you plan to buy a car costing Rs. 10 lakh after 5 years. If you save Rs. 2 lakh each year for 5 years, you will have Rs. 10 lakh at the end of the period, assuming there are no investment returns or changes in the cost of the car.

A company can use the same approach for a different purpose. For example, a company with bonds worth Rs. 50 lakh that mature after 10 years could set aside Rs. 5 lakh each year towards the future obligation, ignoring any interest or investment returns.

These examples show the basic idea: a large future expense can be divided into smaller regular contributions.

The sinking fund formula can be used when the money you set aside earns a specified interest rate. It helps calculate the regular amount required to reach a target over a fixed period.

The formula is:

S = (P × i) / [1 - (1 + i)^-n]

Where:

• S = amount to be saved in each period
• P = target amount
• i = interest rate per period
• n = number of saving periods

For example, suppose you need Rs. 5,00,000 after 10 years and expect your savings to earn 5% per year. If you make one contribution at the end of each year and the return is compounded annually, the formula gives an annual contribution of approximately Rs. 39,755.

This is an illustration, not a guaranteed return. Actual returns can differ depending on where the money is kept.

Some investors may use mutual funds for longer-term financial goals through regular investments or one-time investments. You can explore mutual funds as one possible investment avenue, keeping in mind that mutual fund returns are market-linked.

The purpose of a sinking fund depends on the expense you are preparing for. Common examples include debt repayment, asset replacement and education-related expenses.

Debt repayment sinking fund

You can set aside money towards a known future debt payment. This approach can help you prepare for a large payment instead of arranging the full amount at the last minute.

Asset replacement sinking fund

You can save for the future replacement of an asset such as a car, laptop or household appliance. Regular saving can spread the expected cost over the useful period of the asset.

Education sinking fund

You can create a sinking fund for a known education expense, such as school fees or further studies. The amount and saving period depend on the expected cost and the date when you will need the money.

Retirement planning

Retirement is a long-term financial goal that requires regular planning. Investments can form part of this planning, but retirement planning is broader than a sinking fund for a specific expense.

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An emergency fund should not be treated as a type of sinking fund. An emergency fund is meant for unexpected expenses, while a sinking fund is normally created for an expense you can anticipate.

A sinking fund can help you prepare for expenses that are large enough to affect your regular budget. The purpose is to spread the financial impact over time.

For individuals, common uses include:

• Annual insurance premiums
• Planned home repairs
• Education expenses
• Vehicle replacement
• Major appliance replacement
• Planned travel
• Other known large purchases

Businesses can use sinking funds for debt repayment, bond redemption, major maintenance and replacement of machinery or other assets.

For a planned expense, the important point is to estimate the amount you will need and start saving early enough.

Starting a sinking fund involves choosing one financial goal and creating a regular saving plan. Follow these steps to keep the process simple.

1. Choose a goal: Decide exactly what you are saving for.
2. Set the target amount: Estimate how much the expense is likely to cost.
3. Set a deadline: Decide when you expect to need the money.
4. Calculate your contribution: Divide the target by the number of saving periods, or use the sinking fund formula if your money earns a return.
5. Keep the money separate: Use a separate account or suitable investment so that the money is not mixed with everyday spending.
6. Review your progress: Check your balance regularly and adjust your contribution if your target or timeline changes.

For example, a Rs. 1,20,000 target due in 2 years requires Rs. 5,000 per month when you do not account for any return.

A sinking fund can make a planned large expense easier to manage because you spread the cost over time.

The main benefits include:

• Better planning: You know what you are saving for and how much you need.
• Less pressure on your monthly budget: A large expense is divided into smaller contributions.
• Reduced need for last-minute borrowing: Having money ready may reduce the need to arrange funds when the expense is due.
• Clear financial goals: A separate fund makes it easier to track progress.
• Better preparation: You can plan for known expenses instead of allowing them to disrupt your regular finances.

A sinking fund does not guarantee that you will avoid borrowing. If the expense increases or your savings are lower than planned, you may still need additional funds.

The right place for a sinking fund depends on when you need the money, how accessible it needs to be and how much risk you can accept.

For a short-term goal, keeping the money in a suitable savings account can make it easier to access when required. For a longer-term goal, other options may be considered based on the investment period and risk involved.

Mutual funds are market-linked investments. Their value can rise or fall, so you should not assume that the amount invested will remain unchanged when you need the money.

If you use a mutual fund for a sinking fund, consider whether the investment's risk and time horizon match your goal. The SEBI Riskometer shows the risk level of a mutual fund scheme as Low, Low to Moderate, Moderate, Moderately High, High or Very High.

Do not choose an investment only because it has the potential for higher returns. For a fixed future expense, having the required amount available at the right time is an important consideration.

You can also explore top-performing mutual funds when researching mutual fund options, but past performance does not guarantee future returns.

A sinking fund and a savings account are not the same thing. A sinking fund describes why you are saving, while a savings account is one place where you can keep your money.

The key differences are shown below.

You can use a savings account to hold a sinking fund. You can also use another suitable financial product depending on the goal, timeline and risk involved.

A sinking fund and an emergency fund both involve setting money aside, but they solve different problems. A sinking fund is for an expense you can anticipate. An emergency fund is for an expense you cannot predict.

The differences are easier to understand in the table below.

For example, an annual insurance premium can be planned in advance and funded through a sinking fund. A sudden loss of income would be an emergency and should not be treated as a planned sinking-fund expense.

A sinking fund is a simple way to prepare for a known future expense. You set a target, decide when you will need the money and save towards it regularly.

The most important step is to match your saving or investment approach with the time available and the amount you need. A sinking fund can help you prepare for planned costs, while an emergency fund serves a different purpose.