Anteater,
Ok, I just pretend I am you. This is how I feel or would do. When it comes to BIG MONEY, I would not mingle with family; becasue I value family more than money. These partnerships eventually end up in litigations or in court down the road, the judge order to sell house and split equity. Then a realtor comes in and sell the house with higher fees because of the fightings he/she has to deal with. I personally get assignments to sell to dissolve partnerships like what you are thinking. Not a fun thing for me to do but it's my job. Court orders to sell within timeframe so price is compromised.
I strongly advise you to keep it very CLEAN. The reason, life is all about changing events. What works today could be a tomorrow's nightmare.
Here are a few CLEAN suggestions
a. Pay rent to live in your sister's house.
b. Buy your sister's house free and clear. BUT YOU MUST FEEL THAT THIS HOUSE IS THE BEST HOUSE AND BEST PRICE YOU CAN GET. SO LATER ON YOU DO NOT FEEL SHORT CHANGE AND RESENT YOUR SISTER. Your sister can have the $250K or $500K tax exemption for living in the house 2 of the last 5 years if she sells to you free and clear. Me, I would not even touch this house because I do not want to take any risk with family.
<strong>OK, you are a big risk taker, so here is my comments,</strong>
<strong>1. Does the title work get redone to reflect my name and can it be done without an official sale involved?</strong> Yes, your sister can grant you ownership through joint tenant or tenant-in-common. You have ownership and no liability. Go to any escrow company so they can do the paperwork for you if you are not comfortable with doing the grant deed yourself. Cost is between $75 - $200.
If you make payment for 12 months, you can refi and take your sister's name out of the loan completely. It's going to be a cash-out so it's tricky. Please contact your loan officer to plan this out.
<strong>2. Do I get added to the existing mortgage so I can claim interest write-off?</strong> No, you can not get on the mortgage without refi. If you make mortgage payments and your name is on the deed, you can deduct the interests (make sure there is no double deductions between you and your sister) even if your name is NOT on the loan. Please verify this with your CPA.
<strong>3. Or, do we have to refinance? I don't believe she is planning to take any equity out.</strong> Yes, you can refi now and add your name of the loan; thus on the deed.
<strong>You must have a written contract between you and your sister. I personally would use a real estate attorney to write up a contract. The attorney can spell out all the "what if" situations and resolutions.
Good luck to you.</strong>