Cost of Delaying SIP Calculator

Most SIP conversations start with fund selection. The more expensive question is usually the date on the first instalment. A SIP started today and a SIP started five years later can use the same fund, the same monthly amount and the same return assumption, yet end with radically different corpus sizes. This calculator puts a number on that gap.

What is the cost of delaying a SIP?

The cost of delaying a SIP is the future value of the contributions you did not make, plus the compounding those contributions would have earned. It is an opportunity cost, not a fee. Nobody sends you a bill for it, which is why it is easy to ignore.

Every SIP instalment has two jobs. The first is to add fresh capital. The second is to earn returns for the rest of the plan. An instalment made in year one has 19 more years of compounding in a 20-year plan. An instalment made in year six has 14. The monthly amount is the same, but the time attached to it is not.

That is why the final gap is much larger than the amount you skipped. In the example above, five years of a ₹20,000 SIP is ₹12 lakh of missed contributions. The corpus gap is about ₹98.9 lakh. The rest is lost compounding.

How this calculator measures the cost of delay

The calculator holds three things constant: the monthly SIP amount, the expected annual return, and the total investment period measured from today. It then compares two paths.

• Start now: the SIP runs for the full period.
• Start later: the same SIP runs only for the remaining years after the delay.

The corpus for each path is the future value of a monthly annuity due:

FV = P × ( ÷ i) × (1 + i)

Here P is the monthly SIP, i is the monthly return (annual return ÷ 12), and n is the number of monthly instalments. The final term, (1 + i), reflects the instalment being invested at the start of each month.

A worked example at ₹20,000 a month

The table below uses a ₹20,000 monthly SIP, an assumed 12% CAGR and a 20-year horizon. The only variable is the delay.

These are projections at a constant return, not promises. The direction of the result is what matters: the gap grows faster than the delay itself.

Why the last few years matter more than the first

Compounding is not linear. In the early years, the corpus is small, so the return on it is small. The monthly contribution does most of the work. In the later years, the corpus is large, so the same percentage return adds a much bigger absolute amount.

A delay at the start removes the years when the corpus is at its largest. That is why a five-year delay on a 20-year plan removes roughly half the final corpus, not one quarter of it. The person who starts late is not simply investing for fewer years; they are removing the highest-leverage years from the plan.

Why a higher return cannot fix a late start

It is tempting to compensate for a late start by assuming a higher return or choosing a more aggressive fund. That is the wrong lever. A higher assumed return increases the uncertainty of the outcome, while the missing years are certain. The plan becomes more fragile at exactly the point where it needs to be more reliable.

The same logic applies to a step-up SIP. A step-up is powerful, but it works best when it is layered on top of an early start. It cannot recreate the years that have already passed.

How to catch up if you have already delayed

The calculator gives the extra monthly SIP needed to rebuild the original corpus on the shorter timeline. In practice, there are four levers.

1. Increase the monthly SIP

This is the most direct fix. The calculator shows the exact monthly amount required, so the decision becomes a budget question rather than a guess. If the required amount is unaffordable, do not force it and then stop after six months. Move to the next lever.

2. Extend the goal date

A later goal date gives the corpus more time to compound. For a retirement or education goal, a two-year extension may be more realistic than doubling the SIP. The trade-off is that the goal is delayed, which may or may not be acceptable.

3. Add a lump sum

A bonus, an inheritance or a maturing fixed deposit can shorten the catch-up period. The lumpsum target calculator shows how much one-time capital is needed today for a given future target. Deploy a large lump sum through a systematic transfer plan rather than all at once if valuation risk is a concern.

4. Use a step-up SIP

A step-up increases the SIP amount with income. It is the most sustainable way to catch up because it does not require a sudden budget cut. The SIP calculator lets you model a 5% or 10% annual step-up alongside the delay.

Cost of delaying SIP vs timing the market

A common reason for delay is the belief that the market is expensive. The calculator does not take a view on valuation, but the arithmetic does. A SIP buys units at many different prices. The months when the market is falling are the months when the same instalment buys more units. Stopping or delaying the SIP removes those purchases as well.

If you have a large lump sum and genuinely want to spread entry, use a systematic transfer plan from a liquid fund into the target fund. That keeps the money invested while averaging the entry price. It is a different decision from delaying the monthly SIP.

Who should use this calculator

This calculator is most useful for:

• Someone who has been meaning to start a SIP for a year or more.
• A person who stopped a SIP during a correction and is now restarting.
• A couple comparing a joint goal started today with one started after a house purchase or a career change.
• An investor deciding between increasing the current SIP and starting a second SIP for a new goal.

If you are choosing between goals rather than dates, the target SIP calculator is the better starting point. It works backward from the amount you need.

Assumptions and limitations

The calculator assumes a constant annual return, a constant monthly investment, and no taxes or exit loads. Real returns arrive in a sequence, and a poor sequence in the final years can matter more than the average return. The model also ignores inflation, because it compares two nominal corpus values on the same date. For a goal expressed in today's purchasing power, use the target SIP or goal calculator, which inflates the target first.

Mutual fund investments are subject to market risks. Past performance is not indicative of future results. Use this tool to understand the cost of delay, not to forecast a fund's return.

Manas Money is an AMFI Registered Mutual Fund Distributor (ARN-330576) and NISM Certified Research Analyst, based at 2nd Floor, Madrecha Heights, Lane 3, Road 28, Ram Nagar, Wagle Estate, Thane West - 400604. We manage over ₹110 million in assets for clients across 24+ cities and 7 countries, backed by the 35+ year old Madrecha Group.

If you want help sizing the catch-up SIP or rebuilding a plan that stalled, book a free consultation or read our guide to SIP advisory in Thane. For goal-based structuring, see goals-based investing and financial planning.