When you co-sign a loan for someone else, you take on full responsibility for the debt if they default. Co-signers end up paying the loan 75% of the time when the primary borrower defaults. Co-signing is especially risky for student loans, as many graduates struggle financially and default rates are rising. While it's difficult, the best way to help someone is not by co-signing but by offering a cash gift instead to avoid potential damage to your own finances and credit over many years.