I am considering helping her buy a house (we will both be on the loan and title) in which she will live and also rent out 1 or 2 rooms.From what I've been able to find, I understand that if I make a portion of the mortgage payment, I am entitled to a proportional portion of any personal deductions (e.g. the mortgage interest deduction).I also understand that if a part of a home is used as a personal residence and a part is used as a rental, that the costs are split proportionally in order to determine how much cost is considered personal and how much is considered a cost of the rental.What I haven't been able to figure out is how to treat the costs and income if we share ownership of the house and we both contribute to the payments while she uses a portion as her personal residence while we also rent out 1 or 2 rooms.Can anyone help me understand how to allocate the costs and income? 

You've just gone through an ownership change and have no paper leases.

These might include Owners with Low Financial Stability Scores (FSS) or Seniors with Long-time Ownership.

With real estate, you maintain much more decisionmaking control and although we experienced a wicked housing collapse last decade, many real estate investors can still argue they maintained cashflow and that their respective market didn't feel the same pain others did.The knocks I would have against real estate is it is significantly less liquid and the fees are much higher when it comes to buying, selling and financing.With the introduction of Robin Hood, it's a race to the bottom as brokerages have been slashing trading fees in recent years.In my mind, there is nothing more passive than buy and hold stock ownership, though you may be relying more on capital appreciation, whereas many real estate investors prefer passive cashflow.

Yeah, you can give her $5K walking cash and take the property subject to, but the lender will surely default the note and accelerate with that change in ownership.

What matters most is that the buyer receives a title policy and receives ownership via a warranty deed.  

Length of ownership doesn't come into play here. 

But given the average rent for this home in my area would run $300-$400 more per month I am stuck with do I move and purchase and receive all the tax benefits from ownership?

But you can structure the ownership interest in the LLC so that the borrower doesn't have to have their credit pulled (but they may still need to serve as a guarantor -- it depends). 

I would say no.....it’s like taking over ownership of a house under Land Contract.