Moving out of a state with income tax to a state without before selling, saving 10% or more in taxes. 

Since you have no contract, there is nothing that says you do not have to pay if you are not satisfied, and your spreadsheet would seem to indicate you owe him the money.Similarly, since you paid him for previous work on the spreadsheet, and the spreadsheet shows you owe him for additional work, your argument is not very strong.

Working with a CPA can help you navigate tax implications, and staying focused on long-term planning will set you up for success.

It's low risk and tax free on the gain.

How could this impact tax matters for both companies and the Joint Venture as a whole?

The property will be sold upon completion.Rate:  12.05%Term:  13 months interest onlyARV:  $648,000Loan Amount:  $433,000Processing Fees:  $15,361.64 (3 pts plus processing fees)Escrow Charges:  $3,130.90Insurance/taxes:  $1,722.82Construction Holdback:  $498,361Cash to Close:  $84,762.36 In the OP, you said that the loan amount was $346k.

@Jun Lee One pro that I can think of a solo 401K is there is no UBIT taxes when an asset u invested that had leverage sales.

If they paid Dec rent, then they still owe you for part of Jan (if the lease requires 30 days' notice-if more time is required, then they owe you rent for that period (unless you rent it).

Closing costs, including recording fees, transfer taxes and HOA transfer fees, if any5. 

Quote from @Francisco Milan: Your tax bill ?