The ownership of the house depends on what the original deed transferring title at the time of purchase says and how this ownership is listed in government records where the title transfer deed is registered. Hopefully the
two records are consistent.
In legal systems that descended from British common law (including
the US), the two most common forms of ownership are tenancy in common meaning that, unless otherwise specified in the title deed, each of the owners has an equal share in the entire property, and can sell or bequeath his/her share without requiring the approval
of the others, and joint tenancy with right of survivorship meaning
that all owners have equal share, and if one owner
dies, the survivors form a new JTWROS. Spouses generally own property,
especially the home, in a special kind of JTWROS
called tenancy by the entirety. On the other hand, the rule
is that unless explicitly specified otherwise, tenancy in common with equal
shares is how the owners hold the property. Other countries may have different default assumptions, and/or have multiple other forms of ownership (see
e.g. here for
the intricate rules applicable in India).
Mortgages are a different issue. Most mortgages state that the
mortgagees are jointly and severally liable for the mortgage
payments meaning that the mortgage holder does not care who
makes the payment but only that the mortgage payment is made
in full. If one owner refuses to pay his share, the others cannot
send in their shares of the mortgage payment due
and tell the bank to sue the recalcitrant
co-owner for his share of the payment: everybody is liable (and can be sued)
for the unpaid amount, and if the bank forecloses, everybody's
share in the property is seized, not just the share owned by
the recalcitrant person. It is, of course, possible to
for different co-owners to have separate mortgages for
their individual shares, but the legalities (including
questions such as whose lien is primary and whose
secondary) are complicated.
With regard to who paid what over the years of ownership,
it does not matter as far as the ownership is concerned. If
it is a tenancy in common with equal shares, the fact that
the various owners paid the bills (mortgage payments, property
taxes, repairs and maintenance) in unequal amounts does not
change the ownership of the property unless a new deed is
recorded with the new percentages. Now, the co-owners may
decide among themselves as a matter of fairness that any
money realized from a sale of the property
should be divided up in
accordance with the proportion that each contributed
during the ownership, but that is a different issue.
If I were a buyer of property titled as tenancy in
common, I (or the bank who is lending me money to
make the purchase) would issue separate checks to
each co-seller in proportion to the percentages listed
on the deed of ownership, and let them worry about
whether they should transfer money among themselves
to make it equitable. (Careful here! Gift taxes might
well be due if large sums of money change hands).
