Can part of rental home sale profit be used towards a primary residence purchase without being taxed?

Joe is moving to another state. Joe has two houses, a rental and a primary. Each have good equity. When he moves, he wants to purchase another rental and primary house. If he sells the rental house he understands he has 45 days to reinvest his profit it into a another rental home (1031 Exchange). Without reinvesting the profit, Joe understands he will be taxed on the difference between how much he makes on the sale, minus the outstanding mortgage balance (true profit).

If Joe sells the rental house for $30 and profits $19 (his mortgage balance is $11), can he use $10 of that profit on the purchase of a new rental house, and the other $9 of the profit for his primary house…without being taxed on the $9? He would like to use $9 of the rental house profit towards the down payment on the primary house without being taxed.

Is this possible? Or does the entire $19 profit need to be put towards the rental house purchase to avoid being taxed on it?

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