Choosing the best date of the month to start a SIP is a common question among mutual fund investors. A study of nearly 28 years of BSE Sensex TRI data suggests that the answer may be simpler than many investors think.
The findings show that the timing of a SIP within a month has little impact on long-term performance. Let’s find out what the data says.
What does the finding cover?
WhiteOak Capital Asset Management analysed 10-year rolling SIP returns for investments made on each date of the month in BSE Sensex TRI data from August 1996 to May 2026.
The study calculated the average SIP return (XIRR) for investors who consistently invested on a particular date every month over 10-year periods. The returns are almost similar across all dates.
The highest average return among all dates was 13.42%, while the lowest was 13.36%. That translates into a difference of just 0.06 percentage points, which is statistically insignificant over such a long investment period.
In other words, an investor who chose the best date and another who chose the worst date would have earned a similar return over the long run.
Start, middle or end of the month? It hardly matters
A closer look at the data shows no clear pattern favouring any part of the month.
SIPs made during the first week generated returns between 13.37% and 13.40%. SIPs in the middle of the month delivered roughly 13.39% -13.40%.
SIPs towards the end of the month were marginally higher at 13.41%-13.42%, but the difference was too small to be meaningful from an investment perspective. This shows that in SIP investing, consistency matters far more than timing.
What about F&O expiry-related volatility?
Many investors deliberately avoid or target dates near the monthly Futures and Options (F&O) expiry, believing that increased volatility may offer better buying opportunities.
Instead, the study shows that returns remain within a very narrow range regardless of the chosen date. This suggests that short-term market movements around expiry dates have little impact on the long-term wealth creation potential.
For investors with horizons extending over 10 years or more, monthly volatility events are largely insignificant.
Does splitting the SIP across multiple dates help?
Another popular approach is to divide the monthly investment into multiple SIPs spread across different dates.
Consider three investors each contributing ₹10,000 per month for 10 years. The first invests the entire amount on the 5th of every month, the second on the 20th, while the third splits the SIP into two instalments of ₹5,000 each on the 5th and 20th.
Based on the study’s average SIP returns, all three would have accumulated a corpus of roughly ₹24 lakh by the end of the period. The difference in wealth would be only a few thousand rupees, despite investing the same amount, ₹12 lakh, over a decade.
This suggests that splitting SIPs across multiple dates offers little advantage, as the timing of the monthly investment has a negligible impact on long-term returns.
Focus on behaviour, not dates
The study highlights a broader truth about successful SIP investing. Investors often spend considerable time optimising factors that have little impact on outcomes, such as selecting the perfect SIP date. However, long-term wealth creation depends much more on factors such as:
- Starting early
- Staying invested through market cycles
- Increasing SIP contributions over time
- Maintaining discipline during market downturns
- Avoiding interruptions in investments
So, what is the ideal SIP date?
The best SIP date is not the one that historically generated the highest return. Instead, it is the date that ensures the investor can contribute regularly.
“The best SIP date in our view is when an investor usually receives money in his/her bank account (E.g. Salary Credit Day),” the report mentions.
For salaried individuals, this means scheduling the SIP on the date their salary is credited every month. This reduces the chances of spending the money elsewhere and helps maintain investment discipline.
Across all dates studied, average 10-year SIP returns ranged narrowly between 13.36% and 13.42%, indicating that the timing of a monthly SIP has no impact on long-term investment performance.
Disclaimer: This is purely for educational/ informational purposes and should not be taken as any sort of investment advice. Always consult a SEBI-registered advisor before making any investment decisions.