In the Chapter 13, a co-signer does not have to file the case with you in order to protect your property or set up repayment terms. If the debt is being paid in full through the plan, the co-debtor is released from further obligation once the debt has been fully satisfied. If the debt is not paid in full through the terms of the plan, the creditors can collect the unpaid balance of the debt from the co-signer. In the case of a Chapter 7, if you plan on eliminating the debt (such as surrendering a vehicle), the creditor could still pursue collections from the co-debtor for the balance of the contract. The filing of a Chapter 7 will eliminate the debt of the person who is filing, not the debt of the co-signor (unless the person whom is co-signing is your spouse and has filed the case with you).