Filling of rectification

If you've mistakenly paid tax twice for AY 19-20 due to not submitting challan details initially, you can claim a refund. You'll need to file a rectification request. The process involves submitting a new request under 'Services' > 'Rectification' > 'New Request', selecting the relevant year, and uploading an XML file with the correction details. Ensure you provide reasons in the comment box, and note that no new income or deductions will be accepted. This should be filed under section 139(1) or 139(5) of your last submitted return.