Are the funds for SIP deducted from the bank account?
Funds are deducted from the trading account for stock SIPs. The SIP order will fail if adequate funds are unavailable on the specified date. To ensure the trading account has the necessary funds, the e-Mandate facility can be used. See How do I set up automatic fund transfers from my bank account to my Zerodha trading account?
For mutual fund SIPs, funds should be transferred from the primary bank account. See How to complete payments for the purchase orders on Coin?