Does Changing Your SIP Date Make a Difference to Returns?

The 1st, the 10th or the 25th?

When starting an SIP, a common question is: which date should I choose for the best return? The date can make a difference because the NAV may differ from one day to another. But it is not sensible to build a plan on the assumption that you can know the cheapest date in advance. A better starting point is to ask when your income arrives and how much you actually have left after essential expenses.

How can the date change your units?

In a simplified calculation, units purchased = amount invested ÷ applicable NAV. Investing ₹5,000 at an NAV of ₹100 buys 50 units; at an NAV of ₹95, the same amount buys approximately 52.6316 units. Small differences from charges and rounding are excluded here. Receiving more units at a lower NAV is arithmetic. It does not tell us which date will have the lowest NAV each month.

A short three-month illustration

Two investors invest ₹5,000 each month. Investor A buys at NAVs of ₹100, ₹90 and ₹110 over three months. Investor B buys at NAVs of ₹95, ₹100 and ₹105. Both invest a total of ₹15,000. These are entirely hypothetical prices—not data from any fund, historical period or actual calendar date.

A’s total units: 50 + 55.5556 + 45.4545 = approximately 151.0101. B’s total units: 52.6316 + 50 + 47.6190 = approximately 150.2506. If both holdings are valued at the same NAV of ₹108 after the final instalment, A’s value is ₹16,309.09 and B’s is ₹16,227.07. The difference is approximately ₹82.02.

Now swap the two NAV sequences. The advantage moves to B. This example does not mean the effect of the date is always small. It means the winner depends on the price path. It does not establish a “best SIP date”.

Will your chosen date also be the allotment date?

Do not assume it always will. Under AMFI’s applicable NAV rules, both a valid purchase transaction and the time when the money becomes available for the mutual fund to use matter. This also applies to SIPs. Check the rules for the scheme type, cut-off time and business day; a bank debit alone does not establish that the same day’s NAV applies. AMFI: Applicable NAV and realisation of funds

Consult the AMC’s or platform’s official confirmation and your account statement to understand holidays, bank processing and mandate status. Do not apply a general equity-fund illustration to the rules for Liquid and Overnight Funds.

A practical way to choose your date

Choose a day after your income is credited when sufficient money remains after essential expenses and any minimum-balance requirement. Allow some room if your salary occasionally arrives late. Do not treat an occasional annual bonus like regular monthly income.

When changing the date, check the official instructions to see when the change will take effect. Check the status of the old and new mandates, the next due date and the possibility of a duplicate debit. Do not make a last-minute change on the assumption that every platform follows the same process.

If you want to compare returns

Use the same scheme, plan, option, monthly amount, start and end period, and a common terminal valuation. Examine several starting points over long periods. The return earned on cash left in the bank until a later SIP date, and any skipped instalments, also matter in a fair comparison. Our short illustration excludes interest on cash, tax, exit load and charges.

The takeaway

Choose a date you can comfortably stick to. Rather than repeatedly changing it because one date won in a historical chart, review your contributions, goals and the suitability of your chosen mutual fund. A convenient date does not guarantee future returns, but it can help you maintain a consistent investing routine.

This is general educational information. All prices in the illustration are hypothetical. An SIP does not protect against losses or guarantee returns; understand the scheme and your own risk before investing.