Short answer

Once an IPO application is submitted, the exchange forwards it to the Sponsor bank responsible for the issue, which sends a mandate request to the UPI app to block funds. After the IPO window closes, the Registrar (RTA) verifies the applications to allocate shares and publishes the records on their website.

Sometimes, the RTAs may not display unallotted applications on their portal and may instead show one of the following errors:

No Records found

PAN not found

Bid not found

You can verify your application or mandate status with the application number one day after the bidding date on NSE or BSE.