How SIPs work in India

What a SIP actually is

A Systematic Investment Plan (SIP) is not a product. It is a rail: a recurring mandate (UPI AutoPay or e-NACH) that buys units of a specific mutual fund scheme at a fixed amount on a fixed date. The scheme you buy units in is regulated by SEBI under the SEBI (Mutual Funds) Regulations, 1996, and listed on AMFI's master. The AMC manages the underlying portfolio.

AMFI's monthly note for March 2026 reported 9.72 crore contributing SIP accounts and ₹32,087 crore of SIP inflow in that month (amfiindia.com). The point of that figure: SIPs are not a niche habit — they are the default vehicle for first-time retail investors. AMFI republishes both numbers monthly, so check the current note rather than quoting this one indefinitely.

The cut-off and NAV allocation

Every business day, AMCs publish a single NAV per scheme. The NAV you get on a SIP debit depends on the cut-off time set by SEBI:

• Equity / hybrid / debt (non-liquid) schemes: 3:00 pm cut-off. Funds received and reconciled before 3:00 pm get the same day's NAV; after, the next business day's NAV.
• Liquid / overnight funds: 1:30 pm cut-off, with the previous day's NAV applied for amounts received before cut-off (SEBI circular Apr 2020).

The "funds received" requirement is what actually decides your NAV: the money has to reach the AMC's collection account before the cut-off, not merely leave your bank. UPI AutoPay debits typically land within minutes; e-NACH can take a few hours. That difference — not marketing — is why UPI AutoPay has become the default rail for small SIPs. We have seen distributor-side and press estimates of the UPI share of new SIP registrations, but AMFI does not publish that split, so we do not quote a number for it.

What "rupee-cost averaging" means (and doesn't)

Because your instalment buys more units when NAV is low and fewer when NAV is high, your average cost per unit drifts below the simple average NAV. This is mathematical, not magical. It does not protect you from a falling market — your portfolio value still drops with the index — but it removes the pressure to time the entry. For a 5,000 ELSS SIP over 60 instalments where the NAV ranged ₹40–₹80, the average cost per unit lands closer to ₹52 than to the ₹60 mean.

What actually happens after you press 'Start SIP'

1. Your mandate is registered with NPCI (UPI AutoPay) or your bank (e-NACH). One-time approval.
2. On the SIP date, the rail pulls the amount. UPI AutoPay typically completes in <10 minutes; e-NACH can take 1–2 hours.
3. BSE StAR MF receives the order from your distributor (us) with the EUIN of the soliciting employee. Order ID is generated.
4. If the funds reach the AMC before the day's cut-off, you get today's NAV. Allotment usually shows up the next morning.
5. Units are credited to your folio at the RTA (CAMS or KFin) over the following business day or two, depending on the scheme type. The timeline is the AMC's, not ours — your account statement from the RTA is the authority, and it is the document to reconcile against if anything looks wrong.

Common failure modes

SIPs fail in three places, in order of frequency: (1) insufficient bank balance on the debit date, (2) mandate suspension by the bank after too many failures (typically 3 in a row), and (3) AMC rejection for a non-KYC or expired-KYC investor. The first two are silent — the user often doesn't know until they check holdings months later. We send an SMS on every failed debit plus a fortnightly summary of your SIP health.

Bottom line

A SIP is a habit-building rail, not a product feature. The actual investment quality comes from the scheme you've chosen — the AMC, the category, the expense ratio, the fund manager. Pick the scheme first; pick the SIP date second.