Consider structuring it as a joint venture (JV) or syndication.

Seeking advice here on the best approach, any gotcha's that I'm missing, and overall sanity check... My business partner owns a residential property in Seattle outright (the title is in their name and they paid all ca...

Many investors structure these as joint ventures (JVs) or partnerships rather than syndications, which are typically for larger deals. 

Me and a few folks I met at a mastermind group all went in on a joint account a few years back so we could save money. 

You'd also update or create an operating agreement to specify the ownership percentages and roles of the LLC.Another process would be to leave his LLC as is, create a new LLC for yourself, and then create a joint venture LLC where his LLC and your LLC are the members.

For your next step, you might want to look into seller carry arrangements and joint ventures.

If the LLC is disregarded, meaning the property is owned by the LLC but it gets reported in your personal taxes and you file a joint tax return, than you (or rather your joint tax return) is the tax-payer for the property.

My wife and I file taxes jointly in excess of $300,000/annually from our W2s and another $50,000+ from businesses. 

However, I’m new to navigating such a situation, and I’m looking for guidance on:Collaborating with neighboring property owners to reduce costs and share resources.Structuring deals involving land contributions and joint development efforts.Attracting capital partners for projects like this.I think this could turn into a win-win for everyone involved, but I want to ensure it’s planned and structured correctly.

Probably your best bet will be to do a joint venture with an equity partner.