The short answer
If you have money arriving monthly (a salary), SIP isn't a choice — it's the only option, and it's excellent. If you have a large amount sitting idle (bonus, sale proceeds, maturity), the mathematically better move in a rising market is lumpsum, but the psychologically safer and near-as-good move is to stagger it over 6–12 months.
What each one actually is
A SIP invests a fixed amount every month regardless of market level. You automatically buy more units when markets fall and fewer when they rise — rupee-cost averaging. A lumpsum puts the entire amount to work on day one, so every rupee compounds for the full period.
Worked example: ₹12 lakh over 10 years at 12%
- Lumpsum ₹12L today: 12,00,000 × (1.12)¹⁰ ≈ ₹37.3 lakh
- SIP ₹10,000/month for 10 years (same ₹12L total): ≈ ₹23.2 lakh
Lumpsum wins by ₹14 lakh — but only because we assumed a smoothly rising market. In 2008, a lumpsum invested in January was down ~50% by October; a SIP started the same day bought the entire crash at low prices and recovered years sooner. The gap between the two strategies is really a bet on the market's path, which nobody can predict.
When SIP wins
- Volatile, sideways or falling markets (averaging works in your favour)
- You invest from monthly income
- You're new to equity and a 30% drawdown on a lumpsum would make you exit
When lumpsum wins
- Steadily rising markets (more time in market beats timing)
- Long horizons (15+ years), where entry point matters less
- Debt funds and FDs, where there's no volatility to average
The hybrid most planners recommend
For a windfall: deploy 40–50% immediately, park the rest in a liquid fund, and move it into equity via a Systematic Transfer Plan (STP) over 6–12 months. You capture most of the upside if markets rise and keep averaging power if they fall. And regardless of method, add a 5–10% annual step-up to any SIP — over 20 years it can nearly double the final corpus.
Tax treatment (identical rules, different clocks)
Equity funds: gains after 1 year are LTCG taxed at 12.5% beyond ₹1.25 lakh/year; earlier exits pay 20% STCG. Note that each SIP instalment has its own 1-year clock, so redeeming a 3-year-old SIP means the last 12 instalments may still be short-term.
Try it yourself
Run your own numbers: SIP calculator (with step-up) · Lumpsum calculator (with inflation adjustment).