If I co-sign a loan for a friend or a child what impact does this have on my ability to get a home loan? — Если я подпишусь на заем [заключу кредитное соглашение\] совместно с другом или ребенком, как это повлияет на мою возможность получить жилищный заем?
A cosigner's obligation to repay debt arises only after the borrower has defaulted on the loan; however, cosigning a loan is not without risk. A person cosigning a loan should be comfortable with the borrower's ability to repay the debt.
совместно подписывать (соглашение и т. п.)