According to the 1975 SJC decision, when is a real estate commission due?

A real estate commission is generally considered due when the transaction closes. This is because the completion of the sale signifies that all the conditions agreed upon in the purchase and sale agreement have been fulfilled, and the real estate agent has effectively earned their commission by facilitating that successful transaction. Until the closing occurs, there are often many factors that could prevent the deal from finalizing, so it is logical that the agent's compensation is contingent upon this final step.

The other options touch on important aspects of the real estate process, such as signing agreements and listing properties, but do not reflect the point at which the commission is legally due. Signing an agreement or listing a property might start the process, but the actual earning of the commission is tied to the closure of the sale. The significance of closing is that it confirms both the seller’s and buyer’s commitment to the transaction, thus qualifying the agent for payment.