Do I split mortgage 50/50?

[normay]

Hello,
My husband and I are buying a house with my sister. We are planning on all retiring soon and so this would be our retirement home. We all get along so that isn't an issue. My question is, do we split the the mortgage 50/50 as in my husband and I 50% and my sis 50%? Or 1/3? I know that the answer seems pretty simple, but she is going to have full access to all of the house, even though she will be living in the "guest house".
Of course I look at my husband and I as "one entity" so that is why I say 50/50. So any answers or comments would be greatly appreciated.
thanks,
Norma

 

[odyssey06]

Ideally 50-50 as you and your husband are one "economic unit", and your sister is another...
And presumably this split should also apply to all shared household expenses such as property tax, insurance?

In a 2/3 v 1/3 split, in the sad situation where you or your husband pass away would the surviving partner be expected to still cover 2/3?

Of course you may have to revise this if the sister can only manage to cover 1/3 of the costs and mortgage\downpayent.
Also, if there is a significant difference in size and facilities between the "main house" and the "guest house" it may be fairer to go with a 2/3 v 1/3 split.

If you haven't already you both need to prepare wills outlining what happens should X predecease Y and so on.

 

[2blacklines]

Not a mortgage but when we were in a similar situation regarding renting, we decided 60/40 was the fairest split for rent and all bills were split 3 ways