Editing Security clearance (section)

===National Security Clearance types===
National Security Clearances are a hierarchy of levels, depending on the [[Government Security Classifications Policy|classification of materials]] that can be accessed—Baseline Personnel Security Standard (BPSS), Counter-Terrorist Check (CTC), Enhanced Baseline Standard (EBS), Security Check (SC), enhanced Security Check (eSC), Developed Vetting (DV), enhanced Developed Vetting (eDV), and STRAP.

The BPSS is the entry-level National Security Clearance, and both CTC and EBS are effectively enhancements to the BPSS, with CTC relating to checking for susceptibility to extremist persuasion, and EBS relating to checking for susceptibility to espionage persuasion, the latter being needed for supervised access to SECRET material. The SC again is focused on susceptibility to espionage persuasion, and is required for an individual to have long-term unsupervised access to SECRET material and occasional access to TOP SECRET (TS) material, whilst for regular access to TS the DV, eDV is required. Occasionally STRAP is required with DV.

Those with National Security Clearance are commonly required to sign a statement to the effect that they agree to abide by the restrictions of the [[Official Secrets Act]] (OSA). This is popularly referred to as "signing the Official Secrets Act". Signing this has no effect on which actions are legal, as the act is a law, not a contract, and individuals are bound by it whether or not they have signed it. Signing it is intended more as a reminder to the person that they are under such obligations. To this end, it is common to sign this statement both before and after a period of employment that involves access to secrets.