Pan Aadhar not linked

A user is asking for advice on filing an Income Tax Return (ITR) for FY 2020-2021 when their client's PAN is not yet linked to Aadhar, even after paying a penalty. They are concerned about the time it takes to link PAN and Aadhar and whether it's possible to file the ITR now and link later, or if immediate e-verification is mandatory. The advice given suggests filing an updated ITR and e-verifying within 30 days, though clarification is sought on how this applies to the 20-21 financial year.