Form 10 IC for 115BAA

Https://m.economictimes.com/news/india/cbdt-extends-date-for-domestic-cos-to-gain-22-tax-benefit-under-form-10-ic/amp_articleshow/104657229.cms

I am unsure of AY 2020-21 ITR. But see if this extension circular can help you.
Ideally, if the portal allows you to file then file it and respond to the notice that it's already filed