The question is not clear. Taking a loan in riba is prohibited regardless of the signer and co-signer.

is it permissible to use someone whose income is mostly haram as a co-signer for a loan? Please note that this is a situation in which there may not be any other choice.

Riba | March 19, 2017 4:51 pm
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My friend’s mom was byforced by his uncle (Mothers elder br.) to sign his doc to get a Van on leasing facility… His mom didn’t really sign to get any profit…His mom was byforced to sign..She signed because she cannot break the blood relation..That’s all.. Now that uncle ,he is paying monthly..There r few months left to pay fully..
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We have a business in fruit & veg sector and my dad take control of whole the business and the business deals with interest and it owes a lot money to people that we buy our stock from. Im currently working for my dad and but the business is under my name and i don`t have any control of the business and i cannot bring the business in a halal path and to pay our debts faster or to increase.