In any given fix and flip joint venture, if one partner provides the funds to purchase the house, and the other partner funds the rehab, what kind of deal structure would you consider fair in a split of the profits? 

If the home you live in has a lot of capital appreciation (profit) then you will almost certainly want to sell and take that tax-free (up to $250k for a single, $500k married filing jointly) . 

IRS will view your joint venture as a partnership, and your partnership will file a partnership return(1065).

Also very curious how others have structured joint ventures.

The partners are my husband and myself, and we file a joint return for our 1040.

Here is to a healthy and prosperous 2019!

You can structure equity split.We like to use "shared appreciation mortgages" for our joint venture agreements.

The market here is a bit high, with most multi-family units starting at 380K and up which is a pretty healthy chunk of change.

We got around that problem as my wife handled finances for her mom, had a $100K joint account going back 10 years, so we showed them that, even though we actually used the HELOC for the down at the closing.

Not only found the deal for me, but unloaded it for a fair price and a healthy profit