What are the implications for gift taxes if a joint bank account is opened between including two siblings and their spouses?

[jawlstc1]

My wife and I are building a house on land owned by her family. The two of us will contribute toward the construction costs from the proceeds of the sale of our current home. Her sister and brother in law will also contribute a significant portion of the construction costs, and we’re trying to figure out the best way to go about this. If we set up a joint checking account including my wife, myself, her sister, and her brother in law, would their be any gift tax implications for any of contributing funds to such an account or when paying funds out of the account for the construction of the house?

[Opus 17]

Why are you building house together? Is it for one or both of the families to live in? Is it an investment? If it is only for one family to live in, what happens to the equity provided by the other family?

[rjs]

The situation you describe is more complicated than just how to set up a bank account. You are going to have issues with the construction contract, the ownership of the land and the house, how it is going to be used after it's built (who's going to live in it), and handling the real estate tax, mortgage payments (if any), and other expenses. You need to consult a real estate lawyer and a tax lawyer (two different lawyers), before anyone puts any money anywhere or signs anything.