tax consequences for joined owner

[blueskyus0]

I am planning to sponsor my son to purchase an apartment in NYC. We will be joined owner of this property. He will get a loan under his name alone (I am not co-borrower). I will contribute towards down payment. We file separate tax returns every year. I have the following questions:

1 Can he claim property tax on his tax return without splitting with me?

2 When we sell this house in the future, do we need to split real estate gain/loss? Or one person can claim all?

3 Is gift tax involved anytime at purchase or selling of the house?

[Critter-3]

1 Can he claim property tax on his tax return without splitting with me?  You each can deduct what you actually paid on the mortgage interest and RE taxes.

2 When we sell this house in the future, do we need to split real estate gain/loss? Or one person can claim all?  If you sell a property that you jointly own then each of you will report the portion of the sale based on the ownership %.  Before you sell consult a local RE attorney and/or a local tax pro  to  see what your options are in your state.

3 Is gift tax involved anytime at purchase or selling of the house?  Nothing is being gifted when you buy however possibly when you sell depending on what you do with the titling prior to the sale ... again seek local professional guidance.

[blueskyus0]

what determines the ownership percentage? Is it by verbal agreement? Can the percentage be changed later on?

[Carl]

what determines the ownership percentage?

Generally, it's assumed to be 50/50 unless specified otherwise in a legally binding document of some sort. But I stress, "generally". 

If not specified in writing, other methods include things like what percentage of the down payment each provided by each owner, what percentage of each payment was made by each owner, etc.  Things can tend to get more complicated when your state also taxes personal income.

Overall, I would suggest you both obtain the advice of not only an RE professional, but a tax professional in your local area. Especially if the intent is to rent out the property. You may find it best to form a partnership or multi-member LLC in that case. Doing so allows one to specify the "capital contributions" of each member to the partnership/LLC, as well as specify ownership percentage. It can get complicated when you get into things like general partners and limited partners. I've never got that deep into partnerships or multi-member LLC's myself, so can't be of much help in the more complicated situations.

Overall, with a partnership or multi-member LLC, the "business" will file it's own 1065 tax return and issue each member a K-1, which each member will need to complete their personal 1040 tax return. Turbotax has a separate program called "TurboTax Business" for that. (Not the same as Home & Business, which does not "do" 1065 returns.)

[blueskyus0]

Federal tax law says "If you have a gain from the sale of your main home, you may be able to exclude up to $250,000 of the gain from your income". This is primary home for my son, not me. With joint ownership, can he still get this $250k exception if there is a gain when the property is sold?