Can I have a binding contract?

You can draft a contract to memorialize an agreement for any lawful purpose. But just remember that the agreement will be between you and your brother only. So if he doesn't pay up on his portion of the loan, the loan company will come after YOU, not him. You will then have to sue him to recover any money you have lost. But again, you will be on the hook with the loan company. Definitely talk to an attorney and have them draft a contract for you. I would not recommend you trying to draft it yourself.

Yes, such a contract could be prepared to make your brother liable equally on the loan. In case of a default, you will have to sue to recover 50% share from your brother, which most likely will happen after you've first paid 100% of the default amount to the loan company. It is important to engage an attorney to draft such a contract. You may also consider asking for some sort of security/collateral from your brother depending on the amount you wish to borrow and the proposed loan terms.

Sure, so long as you know that even though you and your brother will have a signed contract with respect to your rights and obligations, ultimately YOU are on the "hook" for the payment of the loan to the lender as the signator and responsible party. You . If the contract is valid and for a lawful purpose, you can pursue the balance owed from your brother. I highly recommend paying an attorney to draft this agreement for you (or both of you if valid disclosure are made and waiver signed). You can find an attorney in your area by searching the "Find a Lawyer" section of this website.