How much due diligence should you do before you submit an offer to the seller? First, let’s make sure we’re on the same sheet of music by defining “due diligence.” Due diligence is the research you will want to do on a home and the property before you close on the transaction. The bottom line is you need to know if there are any serious issues that would cause you to walk away from the property, which is all part of doing your due diligence.