| C&AG | Comptroller and Auditor-General |
| CDI | Chief of Defence Intelligence |
| CESG | Communications Electronics Security Group, GCHQ |
| CIA | Central Intelligence Agency (US) |
| CSI | Ministerial Committee on the Intelligence Services (UK) |
| DIS | Defence Intelligence Staff, MOD |
| FBI | Federal Bureau of Investigation (US) |
| FCO | Foreign and Commonwealth Office |
| GAE | General Administrative Expenditure |
| GCHQ | Government Communications Headquarters |
| HMCE | Her Majesty's Customs and Excise |
| IOCA | Interception of Communications Act 1985 |
| ISA | Intelligence Services Act 1994 |
| IT | Information Technology |
| JIC | Joint Intelligence Committee |
| MATL | Maternity Leave |
| MOD | Ministry of Defence |
| MRP | Security Service Manual of Recording Policy |
| NAO | National Audit Office |
| NAP | New Accommodation Project (GCHQ) |
| NATO | North Atlantic Treaty Organisation |
| NCIS | National Criminal Intelligence Service |
| NIS | National Investigation Service (HM Customs and Excise) |
| NSA | National Security Agency (US GCHQ equivalent) |
| OCE | Other Current Expenditure |
| PAC | Public Accounts Committee |
| PES | Public Expenditure Survey |
| PFI | Private Finance Initiative |
| PSA | Property Services Agency |
| PSIS | Permanent Secretaries' Committee on the Intelligence Services |
| REU | Restricted Enforcement Unit (DTI) |
| SIS | Secret Intelligence Service |
| SIV | Single Intelligence Vote |
| SIVR | Single Intelligence Vote Review |
| SO(SSPP) | Sub-committee of the Official Committee on Security, on Security Service Priorities and Performance |
| SUPL | Special Unpaid Leave |
| VX | SIS, Vauxhall Cross |
| WMD | Weapons of Mass Destruction |
| Y2K | Year 2000 problem/Millenium bug |
