You're bound by the terms of the contract you originally cosigned for unless you approach the creditor and have it refinanced into your own name, in my opinion. If you're concerned that the other party won't repay as agreed, you can also approach the creditor and ask to do the same. The only way to adequately assure that account is being paid on time is to either monitor status directly with the creditor (you're entitled to account information and most lending institutions offer automated account status via telephone or even Internet,) conduct regular credit checks on yourself (that can get costly and drive your FICO scores down) or refinance the loan into your own name, based on your own 'credit merit.' If there are no issues with the account, you're likely to face some resistance without the other party's cooperation and a great deal depends on your own financial situation and past credit history. It also depends on whether or not you're first in position on the contract as well. (Quite a few creditors insist on dealing directly only with the primary account holder; it depends on how the loan agreement reads and federal financial privacy act laws are very stringent upon how much information can be disclosed.)

Personally, I'd suggest you have the account information set up in your name as well, either via telephone or even the Internet, so you can access it on a regular basis. You might want to make sure that's in place as soon as possible, while the 2 of you are still on speaking terms. You've posted nothing to suggest the account's in trouble at this point, but you show a remarkable sense of responsibility in voicing concerns of the future. FYI: as a whole, most creditors don't distinguish between the types of 'bad debts,' (barring bankruptcies and foreclosures, of course.) Defaulted student loans aren't the worst thing to ever happen in the credit sense, but they do contribute towards derogatory ratings and depending on your jurisdiction, can take up to 10 years to disappear from your credit history. Taking steps now to avoid that shows a certain credit responsibility & maturity. Kudos to you for looking ahead.

Just a few opinions/suggestions here. Good luck to you.