Your investor buyer wants to identify properties to purchase, then to use as an investment, placing a tenant in the property. The investor buyer makes an offer to a seller, which is now accepted and in escrow.

Question: May the buyer now list the property for rent, and even show it during the escrow period?

Yes.

Let's assume that the property is vacant. Must they wait until they close on it and have title, or can they list it now and show it?

Certainly, unless the contract they wrote with the seller forbids that activity the buyer has the right to market the property. It would be better to obtain the sellers permission, especially if the buyer wants access to show the property, but again, that is not absolutely required. Any such investor buyer would be considered an owner-in-acquisition. 

A buyer in escrow, anticipating a successful close, has an equitable interest in the property. While they do not have title to the property, an equitable interest provides them with certain rights, which includes the right to list it for sale or lease.

That being said, if that investor, rather then rent the property, is more inclined to fix it and flip it, the same rules exist. Just be mindful of the current seller having a form contract with the buyer for, let’s say, $624,000. That buyer wants to fix it, flip and sell it for, let’s say $810,000. The current seller might see that and wonder why they could not sell it for that amount and might be inclined to attempt to cancel the current escrow. While they do not have a lot of options to cancel a contract, they could dig in their heels and not provide the buyer with any repairs, concessions or any benefit, in the hopes the buyer would cancel. This author recommends not listing it for sale until the escrow closes, for that very reason.

Any such listing, and certainly any contract they execute with a buyer or tenant must contain a disclosure that the seller is acquiring title but does not yet have title, and a contract for sale or lease should be contingent on the seller or landlord obtaining title. There should be no prepossession, a tenancy could not begin until the client owns the property, and while a buyer might be allowed to do inspections and a walkthrough, they would not be allowed to begin any work or move anything into the property. If a lease that the investor executes requires the landlord to redecorate, repair, paint or clean, that should not commence until after they own the property.

Be sure to discuss any potential transaction such as this with your broker.