There is no federal regulation that prohibits this as the law that prohibited a surcharge on credit card purchases expired back in 1984. However, both Visa and MasterCard allow a merchant to offer a discount to customers who pay by cash or check, but in most cases they say a merchant cannot charge more for putting it on plastic or that would be a VIOLATION OF THE MERCHANT AGREEMENT.

All card associations require that merchants accept card payments at par value, without giving preference to other methods of payment such as checks. That is, a merchant may not impose a surcharge on the purchaser when they pay by card. The only discount that may be given is for payment by cash, which should be carefully considered before being implemented in light of fairness, operational, security, and internal control issues.

Merchants must adhere to minimum acceptable business practices. In addition to the rules imposed by the card associations there are other prudent business practices that must be set up and followed by each card-accepting department / unit. Internet card acceptance has its own additional requirements. There are additional requirements mandated whenever a merchant wishes to accept card payments through its Web site. This is because of the different nature of the online medium – the speed, volume, and electronic character of these transactions require much stricter attention to security and fraud than is customary for in-person payments.

i tried this and found it to be illegal. even when you see those signs...minimun cc transaction 10$ that is a no no too.

But it is a very bad idea, because you will be responsible for the debt if he does not pay. But you say.....
"I know my brother will pay me - that's not the issue"

If you search this site you will see dozens of people who thought the same as you but are not stuck for debt because the other person actually did not pay...Just something to think about.

BTW, I think this is a bad idea - because if something happens to your brother (even something like a car accident or something beyond his control), you are now legally responsible. I don't believe in mixing money and family - too many tragedies and horror stories.

I am concerned however that you were talking about transfers for a couple of years....
The longest that I have seen the 0% rate is for ONE year.....
if you are late or if you miss a payment, that interest rate defaults immediately to 22% or something equally vile.
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I get it that this is your brother but could you have him sign something for you in case he gets amnesia after the transfer.
(you can tell him your credit card company requires it...you might not need it but it would be better to have it than to not have it)...This kind of foresight will make sure that the two of you stay close.....

also, this will be pointless to 'bail him out' unless he (your brother) cuts up the offending card (or gives it to you) so that you arent doing this kind of favor for the rest of your life.
Read on here how many people take out HELOC (home equity loans) to clean up their credit only to find a way to charge up the same cards all over again!

Further, make sure that you have at least one months expenses (preferably from him) for YOUR card set aside each month so that even if he is late paying YOU, you can still make that payment on time.

Lastly, I am not sure how much debt he has thus there is no way to speculate how this will effect your credit BUT
If your limit on this card is (lets say) 10k and you transfer 8k. Your credit rating will go down slightly (or maybe quite a bit depending on your other debts)

Not a major deal unless YOU have a major purchase (house car) in the near future.
This transfer might lessen the amount that you could qualify for.

But again to answer your question YES you can do this!
(I hope your brother knows how lucky he is to have you.....when I first graduated from college, I needed a cosigner for my car....my mom agreed to do it and the guy at the dealership tried to warn her NOT to do this... he told her that he would NOT even cosign for HIS own mother)
I guess I knew how serious cosigning was but HE really drove it home for me. I was not the case that he was trying to get me to pay a higher interest rate...if I did not have her I was NOT getting the car at all.
I say that because what you are doing is BIGGER than that.
IF I had defaulted on that car loan my mother could have ducked and dodged the bill (maybe filed bankruptcy or whatever.....YOU WONT BE ABLE TO DO THIS because once you transfer it this debt becomes YOURS exclusively)

Pre-determining interest rates

Most balance transfer offers are good for only the first 6-9 months of enrollment. At the conclusion of the introductory rate, the card will convert to a more standard rate, typically between 14-20%. It is important that you determine what the interest rate is going to be once the intro rate is over. If you are not sure what interest rate the card is going to be charging at the conclusion of the intro offer, call the issuer and find out.

New purchase interest rates don't equal the balance transfer rates

The intent of transferring credit card balances is to obtain a lower interest rate and eliminate your debt quicker. It is important to note that the balance transfer interest rate is not going to be the same for new purchases made with the credit card. In fact, new purchase rates are going to be higher. Also, payments that you make towards your credit card bill are going to be applied towards the balance transfer debt first, until they are eliminated. As a result, you are going to end paying a lot of money in interest costs for new purchases. It would be wise for you to pay off all of your balance transfers prior to making any new purchases with your credit card. read more about it at: http://www.credit-card-gallery.com/article/173,Credit_Card_Balance_Transfer_Tips