SIP basics
How a Systematic Investment Plan actually works
A SIP is not a product and not a scheme. It is an instruction: invest a fixed amount, on a fixed date, into a fund you have chosen. Everything else follows from that one sentence.
Ask ten people what a SIP is and eight will answer that it is a type of investment. It is not. A Systematic Investment Plan is a standing instruction to your bank and the fund house: on the 5th of every month, take ₹5,000 from this account and buy units of this scheme. The scheme is the investment. The SIP is only the delivery mechanism.
That distinction matters, because it tells you what a SIP can and cannot do. It can impose discipline, spread your entry across market levels and remove the daily decision of whether today is a good day to invest. It cannot make a poor scheme perform, and it cannot protect you from a falling market.
What happens on the day your SIP runs
Three things happen, in order. Your bank debits the amount under the mandate you signed. The fund house receives the money and applies that day’s Net Asset Value — the per-unit price of the scheme. You receive units equal to the amount divided by the NAV.
Because the NAV changes daily, every instalment buys a different number of units. When the market is down and the NAV is low, your fixed ₹5,000 buys more units. When the market has risen, the same ₹5,000 buys fewer. Over years, this produces an average purchase price lower than the average NAV over the same period — the effect usually called rupee cost averaging.
| Month | NAV | Units bought |
|---|---|---|
| January | ₹50 | 100.00 |
| February | ₹40 | 125.00 |
| March | ₹45 | 111.11 |
| April | ₹55 | 90.91 |
| May | ₹50 | 100.00 |
₹5,000 a month for five months is ₹25,000 invested and 527.02 units held. The average NAV over those months was ₹48.00; the average price actually paid was ₹47.44. The gap is small over five months. Over ten years of instalments through several market cycles, it becomes meaningful.
The part that is easy to miss
Rupee cost averaging works in your favour only if you keep investing when the market falls. Stopping a SIP during a decline removes exactly the instalments that would have bought the most units. That is the single most expensive mistake we see in client portfolios.
Why the monthly date matters less than you think
Investors spend a surprising amount of energy choosing between the 1st, the 5th and the 25th. Studies across long periods find the difference between SIP dates to be negligible — a fraction of a percent over a decade. Choose a date two or three days after your salary credit, so the mandate never bounces, and stop thinking about it.
How long a SIP needs to run
Equity returns are erratic over short periods and less erratic over long ones. A three-year SIP in an equity scheme can end below the amount invested; this is not unusual and not a failure of the method. Over rolling ten-year periods, Indian equity indices have historically been positive far more often than not — though past behaviour is not a promise about the future, and no honest distributor will tell you otherwise.
The practical rule we use with clients: if the money is needed within three years, it does not belong in an equity SIP. Put it in a debt or liquid scheme, or a fixed deposit, and accept the lower return in exchange for knowing roughly what you will have.
Step-up: the change that does most of the work
A flat SIP ignores the fact that your income rises. A step-up SIP increases the instalment by a fixed percentage each year — commonly 10%. The arithmetic is worth seeing rather than describing.
| Structure | Monthly start | Invested over 20 yrs | Illustrative value |
|---|---|---|---|
| Flat SIP | ₹10,000 | ₹24.0 lakh | ₹99.9 lakh |
| 10% step-up | ₹10,000 | ₹68.7 lakh | ₹2.26 crore |
Both assume 12% per annum, compounded monthly, purely for illustration. The step-up version invests more, so a larger corpus is expected; the point is the scale of the difference for an increase most people barely notice in their monthly budget. You can run your own figures in the step-up SIP calculator.
What a SIP does not do
- It does not protect against loss. If the scheme falls, your holding falls.
- It does not choose the scheme for you. The SIP is the instruction; the scheme selection is the decision that actually drives the outcome.
- It does not remove tax. Equity-oriented fund gains attract LTCG or STCG depending on holding period, and each instalment has its own holding period.
- It does not suit every goal. Short-horizon money belongs elsewhere.
Starting one
You need a completed KYC, a bank account and a decision about scheme and amount. The paperwork takes under an hour and is done once. The decision about how much, into what, and for how long is the part worth spending time on — preferably before the first instalment rather than after the first fall.
If you want to see what a particular amount could become over a particular period, the SIP calculator will show the projection and let you save it as a PDF. Treat the output as arithmetic on an assumed rate, not as a forecast.
Common questions
What is the minimum amount for a SIP?
Most equity schemes accept ₹500 a month; some accept ₹100. The minimum is set by the scheme, not by the distributor. Starting small is reasonable — the habit matters more than the first instalment.
Can I stop or pause a SIP?
Yes. A SIP can be paused or stopped at any time with no penalty, usually with a few working days of notice. The units you already hold stay invested until you redeem them.
Does a SIP guarantee a return?
No. A SIP is a way of investing, not a return. The money goes into a mutual fund scheme whose value moves with the market, and the final value can be lower than the amount invested. Mutual fund investments are subject to market risks.
Is a SIP better than a lumpsum?
Neither is better in the abstract. A SIP suits money that arrives monthly, such as a salary. A lumpsum suits money you already hold. Most households end up using both.
What happens if I miss an instalment?
Nothing serious. The instalment is skipped and the SIP continues next month. Your bank may charge a fee if the mandate bounces for want of balance, so it is worth setting the amount at a level you can sustain.
How long should a SIP run?
For an equity scheme, plan for at least five to seven years. Shorter than that, and the return is decided largely by where the market happens to be on the day you redeem.
Work through your own numbers