Keeping all the profit.

[Jeffrey Townsend]

BP family, If I was to purchase a home to eventually flip (house hack) how long would I need to live there in order to not get Tax's taken from the flip profit?

[Lynn McGeein]

From the IRS Publication:

Eligibility Step 2—Ownership

Determine whether you meet the ownership requirement. If you owned the home for at least 24 months (2 years) during the last 5 years leading up to the date of sale (date of the closing), you meet the ownership requirement.

So you don't have to own it for 5 years.  The 5 years comes in if you, for instance, lived in it 2 full years, then rented it out for 3, then sold before the 5 year period, you would still qualify for the full amount.