Most explanations of a SIP stop at “a fixed amount is invested every month”. The questions investors ask later are more practical. Why were my units allotted later than the debit date? What happens if my account is short one month? This guide answers those.
Key points
- A SIP is a standing instruction to debit your bank account. It can be stopped.
- Units for an instalment are allotted at the NAV of the day the money reaches the scheme before the cut-off time, which may be later than your SIP date.
- If a debit fails, no units are bought for that instalment. The units you already hold are not affected.
- Your bank may charge for a failed debit, and repeated failures can lead the fund house to cancel the SIP under its terms.
- Choosing a SIP date soon after your income arrives helps to avoid failures.
What you set up
Starting a SIP involves two things.
- A SIP registration with the fund house for a scheme, an amount, a date and a frequency.
- A bank mandate that authorises debits from your account up to a limit you approve. One mandate may serve more than one SIP if its limit is high enough; your bank or the fund house can confirm.
The mandate can take some days to be registered by your bank, so the first instalment is often paid separately or the SIP starts from the following month.
What happens on the SIP date
- A debit request is sent to your bank under the mandate.
- Your bank debits your account if the balance is sufficient.
- The money moves to the scheme’s bank account.
- Units are allotted at the applicable NAV and added to your folio.
- You receive a confirmation, and the transaction appears in your account statement.
If the SIP date falls on a non-business day, the instalment is normally processed on the next business day. The fund house’s SIP terms state the rule.
Which NAV the instalment gets
SEBI’s Master Circular for Mutual Funds dated 20 March 2026 (paragraph 9.4) says a day’s NAV is assigned only if both the application and the funds have reached the scheme before the cut-off time. AMFI illustrates this with a SIP dated the 10th: units are allotted at the NAV of the 10th only if the money is credited to the mutual fund’s bank account before 3:00 pm that day. Otherwise a later day’s NAV applies. Liquid and overnight schemes follow different timings.
So a gap between the debit and the allotment can occur. It reflects how long the money took to travel. It is not an error. What NAV means covers the cut-off rule in more detail.
If an instalment is missed
Common reasons for a failed debit are a short balance, a mandate limit that is too low, and a mandate that has expired or been cancelled.
What happens:
- No units are bought for that instalment.
- Your existing units stay as they are. A missed instalment does not reduce or cancel anything you already hold.
- Your bank may charge you for a failed mandate debit. The charge is set by the bank, so check its schedule of charges.
- The SIP normally continues and the next instalment is attempted on the next date.
- Repeated failures can end the SIP. Fund houses may cancel a SIP after a number of consecutive failed instalments. The number is set out in the SIP terms and scheme documents, so check it instead of relying on a figure you have heard.
A missed month is not a disaster, but it does mean that month’s investment did not happen. If your goal depends on a certain amount going in, make it up when you can with an additional purchase.
If you know money will be tight
- Pause. Some fund houses allow a SIP to be paused for a stated number of instalments. Availability and terms differ.
- Reduce. Start a new SIP for a smaller amount and stop the old one.
- Stop. A SIP can be stopped by placing a cancellation request. The request has to reach the fund house some days before the next date, as set out in its SIP terms, so place it early. Stopping affects future instalments only.
Stopping a SIP because markets have fallen is a different decision from stopping because cash is short. When the NAV is lower the same instalment buys more units, though that is no protection against a further fall.
Habits that prevent failed debits
- Set the SIP date a few days after your salary or regular receipts arrive.
- Keep the SIP account separate from the one you spend from, or keep a buffer in it.
- Set the mandate limit with room for a future increase.
- Note the mandate’s end date and renew it in time.
- If your income is irregular, choose an instalment you can meet in a weak month and add lumpsums in strong ones. See investing when earnings vary.
Risk note
A SIP does not protect against loss. Units bought through a SIP fall in value when the market falls, like any other units.
Frequently asked questions
Is there a penalty from the mutual fund for missing a SIP instalment?
No units are bought for that instalment. Your bank may charge for the failed debit under its own rules. Check the SIP terms of the fund house for anything it applies and for what follows repeated failures.
Will my SIP be cancelled if I miss one month?
A single failure does not normally end a SIP. A run of consecutive failures can. The number is stated in the fund house’s SIP terms.
Can I change my SIP date or amount?
Usually by registering a new SIP with the new details and cancelling the old one. Some fund houses offer a direct change facility.
Why does my statement show a different date from my SIP date?
Because units are allotted on the business day the money reached the scheme before the cut-off time, which can be later than the debit date.