question about being an uneven partner in a flip

[Corey Demuth]

Theoretical question for the experts:

One party owns a property and wants to do some improvements and then attempt to flip it for a profit. However, that person does not have the capital on hand to do the improvements. Another party may be willing to provide the capital for the improvements, in exchange for a small percentage of the profits upon sale of the property. If both parties agree to this arrangement, what needs to be done legally and for tax purposes?