SIP vs Lump Sum: Which Is Better, and When Does It Actually Matter?
For monthly salary, there's no contest: invest it as it arrives. The real question comes up when a bonus, FD maturity or inheritance lands all at once. Here's what the numbers say, and a calm way to invest it.
Ram
"SIP or lump sum?" sounds like one question, but it's really two:
- Money you earn every month. There's no choice to make here. You can't invest your salary until you've been paid it, so investing it monthly is a SIP.
- Money you already have: a bonus, a maturing FD, an inheritance, savings sitting in your bank account. This is where the real decision is.
This post is mostly about the second one.
General information, not personalised advice.
The comparison most articles get wrong
You'll often see something like this: "₹12 lakh invested at once for 10 years at 12% becomes ₹37 lakh, while a ₹10,000 SIP for 10 years becomes only ₹23 lakh, so lump sum wins!"
That's not a fair comparison. The lump sum had all ₹12 lakh working from day one, while the SIP money arrived bit by bit over ten years. Of course it grew less. This tells you nothing about which strategy is better. It only tells you that money invested earlier has longer to grow.
The fair question is: if you have ₹12 lakh today, should you invest it all now, or spread it out over the next several months?
What history says
Since markets have risen more often than they've fallen, investing a lump sum straight away has historically done better than spreading it out roughly two times out of three. Vanguard's well-known study of US, UK and Australian markets found that, and the logic holds for any market with a long-term upward trend. Money waiting to be invested is money not in the market.
But the one time in three hurts. If you invest everything and the market falls 25% the following month, you're looking at a ₹3 lakh paper loss on ₹12 lakh, right away. Some people shrug that off. Many sell in a panic, which is far worse than either strategy.
So the honest answer is:
- Purely on expected returns, invest the lump sum promptly.
- If a sharp fall soon after would make you sell, spread it out. You give up a little expected return to make the plan one you'll actually stick to.
A practical middle path: park it, then transfer it
If you have a lump sum and you're nervous, don't leave it in your savings account while you decide.
- Put it in a liquid or overnight fund at the same fund house as the equity fund you plan to buy. It earns close to fixed-deposit returns and can be withdrawn any time.
- Set up an STP (Systematic Transfer Plan), which automatically moves a fixed amount from the liquid fund into your equity fund every week or month.
- Keep it short: 3 to 6 months is typical. Spreading over two years means most of your money sits out of the market for too long.
This way, the waiting money is still earning something, and nothing depends on you deciding the "right moment".
What about waiting for a crash? People who keep cash aside "for the next correction" often miss more upside while they wait than they gain from buying the dip. If you want to put in extra when markets fall, add it on top of your regular SIP. Don't hold back your regular investing to wait for it.
Valuations: a note of caution
You'll see rules like "invest a lump sum when the Nifty P/E is below 20, use an STP above 25". Valuation does affect future returns on average. But be careful with exact thresholds: NSE changed how the Nifty P/E is calculated in 2021 (moving to consolidated earnings), so older "safe" and "expensive" levels don't directly carry over.
At most, use valuation to decide how long an STP should run. Don't use it to decide whether to invest.
The COVID crash: why SIPs win on behaviour
In March 2020, the Nifty fell nearly 40% in about a month. Investors who kept their SIPs going bought units at the lowest prices in years, and the index roughly doubled from its March low within about a year. People who stopped their SIPs "until things settle down" missed exactly those units.
That's the real strength of SIPs. It isn't a mathematical edge. It's that a SIP keeps you investing on autopilot through the moments when your instincts tell you to stop.
How it's taxed (equity funds)
Each SIP instalment, and each STP transfer, counts as a separate purchase with its own holding period. Redemptions are counted first-in, first-out.
- Held more than 12 months: long-term capital gains, taxed at 12.5% on gains above ₹1.25 lakh a year.
- Held 12 months or less: short-term capital gains, taxed at 20%.
A lump sum starts a single clock, so it all becomes long-term together. A SIP's newest instalments will always be short-term for their first year. Over long horizons, the difference is small. It only matters if you redeem soon after investing.
So, what should you do?
| Your situation | What to do |
|---|---|
| Monthly salary to invest | Monthly SIP, automated |
| Bonus or FD maturity, comfortable with ups and downs | Invest it promptly, in one go |
| Same, but a fall next month would rattle you | Liquid fund + 3–6 month STP |
| Money you need within ~3 years | Neither. Keep it in debt funds or deposits |
| Waiting for a "crash" to invest | Don't. Invest on schedule, and add extra when falls happen |
You can model both in the SIP calculator and the lump sum calculator. Just remember to compare like with like: the same amount of money, available at the same time.
