My husband and I want to refinance our mortgage and add my brother so we can use his income as well to get a lower rate. Can we do this? Is there a fee other than closing costs, etc? Can he quick deed it back to us later?

You can't just "add" your brother. You have to "sell" him a share of your home so he is on the deed. So you get a new mortgage for the new ownership.

However, if it is not a market value sale (in other words, he pays you a fair price for his share) then there may be tax or legal consequences.

Yes he can quit (not quick) his share back to you at some future date, but again you need to pay him market value for his share. Plus the mortgage lender will have to approve.

It is possible for your brother to be a co-signor on the mortgage loan without him being added to the deed. You can check with the bank whether this will get you a lower rate. However, if I was your brother I would say no to this proposal, as it would put me on the hook for potentially having to pay the mortgage without having anything in return.

As for selling or gifting a share to your brother so that he becomes a co-owner (joint tenant with you) as ScottGem suggests - yes, there may be tax consequences but it's unlikely, assuming that the amount of equity you have in the house is small. Your equity is the fair market value minus the outstanding mortgage loan balance - if that amount is less than $78K there are no tax consequences at all for gifting him a 1/3 share - both you and your husband would each gift him 1/3 of your half of your equity, and if that amount is less than $13K you're fine tax-wise. If the equity in the house is greater than $78K post back and we can go into more detail on the consequences of gifting him a share.

You can add your brother to the loan when you refinance by putting him on the note, however, to get him out of the loan again the only way would be to refinance again. You cannot remove a person that is on the note of a loan by simply filling out a quit claim deed. Quit claim deeds are mostly used so that if one of the borrowers is no longer responsible for a loan (for example through divorce) then that person won't have to sign paperwork that would be needed otherwise to follow different processes, such as short sales, modifications, or deed-in-lieu's... but it will still not remove the person from the loan.