The NAO is publishing a series of 24 guides, aimed at newly elected MPs joining select committees to examine the work of government departments.
Designed to give an accessible overview, each short guide focuses on what the department does, how much it costs and key developments in its areas of work.
The NAO has already produced guides on departments including the Home Office, Ministry of Defence, the Department of Health and the Department for Education, as well as cross-government guides covering issues such as regulation and environmental protection and sustainability.
The remaining guides are set to be published throughout October and shared with MPs – as well as members of the public and journalists – through the NAO’s website and on Twitter.
The clerk of each select committee will also circulate the guides to MPs, while the NAO is liaising with the House of Commons library on distributing them.
Stephen Luxford, senior press officer at the NAO, explained: "After the election there was a big changeover, with new MPs who may or may not know much about the department for which they are on the select committee. The guides are deliberately written in an accessible way and, while they are a resource for Parliament, the project goes much wider. Each guide is meant to be accessible to MPs, the public, researchers and journalists."
The guides are designed to be interactive, so that readers can focus on the information most valuable to them, rather than having to trawl through the whole document.
Each document covers data such as the department’s spending costs, staff numbers and projected savings, as well as looking in depth at programmes of work and how they are delivered.
A recently published guide to the Ministry of Defence reveals that its annual budget is £35bn, with a projected spend of £178bn over the next ten years, and that it employs more than 250,000 people, of which 58,000 are civilian staff.
The NAO’s guides also include issues that MPs might want to consider in their scrutiny of the department, such as how Brexit will impact the department, changes in legislation or regulation and extra demand on the services provided under the department.
In addition to tweeting from the main NAO Twitter account, each guide is being sent directly to key journalists who cover the individual government areas, to use for information and share with their networks.
"Communication is paramount to us, as that way we can hold government to account," added Luxford.