How can I submit the investment proofs to I T dept

Hello Professional Friends

(1)  If I did not submit 80c investment proofs to my employer (after FEb2021, they wonot accept), (2) but I will mention the same in my  ITR  FY 2020-2021, and I will cliam refund thro online.

(3) My question is how can I submit the investment proofs  to I T dept? or not need to submit?

Adv Thanks

Balaji Subbu