How do I add a co-signer to my loan? September 12, 2020 22:34 Updated For guidance on how to add a co-signer, contact us via chat or by phone at (855) 456-7634 once you’ve logged in. Related articles How long will adding a co-signer to my loan take? Can I add a Cosigner? Do you require or accept co-signers for Student Loans? How do I add a co-signer after submitting my application? Can I refinance previously consolidated loans with SoFi?