SPD stands for Single Procurement Document. An SPD is a questionnaire that public sector buyer’s send to bidders as part of their procurement exercise. The responses received are used by the buyer to assess whether the bidder will be able to supply the contract.
Historically the SPD process is something that bidders have asked questions about. As a result, and for ease of access, SPD summary information is available from the top of every Supplier Journey page.
To access this information, you need to click on the down arrow beside the SPD menu heading. You are then shown several page options: SPD Guidance, SPD Summary and Hints, SPD FAQs, that you may click on to access further information on the SPD

More detailed SPD guidance can be found in Single Procurement Document.