For non-auditable cases, DSC is not mandatory. If the DSC is used while uploading the return, the return will be treated as legally filed immediately after uploading. However in case, an individual does not have a DSC, he/she can still file the return electronically, but, in this case, a signed copy of ITR-V has to be sent to ITD CPC, Bengaluru within stipulated time. After receiving the signed copy of ITR-V at ITD CPC, return will be treated as legally filed.
Digital Signature, eToken, Income tax return Explained the use of digital signature in certain return filings.