After you complete your payment, you become eligible for the allotment of shares. But, your application might get rejected due to the following reasons:You have applied for an IPO twice or more times using the same PAN card.The UPI ID that you have used is not registered with your PAN Card, or it is not registered with SEBI. You can check which UPI IDs are registered with SEBI here.On the day of allotment, your Demat account was frozen/closed/suspended.You have applied for the IPO through an incorrect category (e.g. if you applied under the employee category, even though you are not an employee of the company).