There are five main levels of UK national security vetting: the Accreditation Check (AC), Counter Terrorist Check (CTC) (with its equivalent Level 1B), Security Check (SC), and Developed Vetting (DV), plus two enhanced variants: enhanced SC (eSC) and enhanced DV (eDV). Underpinning all of them is the Baseline Personnel Security Standard (BPSS), which is a pre-employment screening rather than a formal clearance. Clearances are managed by United Kingdom Security Vetting (UKSV), the government’s main vetting provider, and you cannot apply for one yourself: an employer must sponsor you for a role that requires it.
This guide explains each level in order of depth, what it lets you access, and how long it lasts. For the two levels most defence employers ask for, see the dedicated guides to SC clearance and DV clearance.
The hierarchy at a glance
| Level | Formal clearance? | Access | Reviewed/renewed |
|---|---|---|---|
| BPSS | No (screening) | OFFICIAL; exceptional supervised SECRET | Per employer |
| AC | Yes (aviation) | Airport security restricted areas | Up to 5 years |
| CTC / Level 1B | Yes | Counter-terrorism-sensitive posts | Up to 10 years (5 for some contractors) |
| SC | Yes | SECRET; occasional supervised TOP SECRET | Up to 10 years (7 for some contractors) |
| eSC | Yes | As SC, with added assurance | Per role |
| DV | Yes | Frequent, uncontrolled TOP SECRET | Up to 7 years |
| eDV | Yes | Above DV, very limited posts | Per role |
Baseline Personnel Security Standard (BPSS)
BPSS is the foundation. It is not a security clearance, but it must be completed before any of the formal clearances at CTC level and above can begin. Responsibility for BPSS sits with the employing organisation, not UKSV.
It verifies four things: your identity, your right to work in the UK, your employment history, and your unspent criminal record. It allows access to OFFICIAL information, and — with written authorisation — exceptional supervised access to SECRET material. Many defence and public-sector roles ask for BPSS as a minimum even where no higher clearance is needed.
Accreditation Check (AC)
The AC is a specialist clearance used in aviation security, for staff who need an airport identification card granting unescorted access to the security-restricted areas of UK airports, who deliver UK aviation security training, or who validate air cargo standards overseas. It is normally valid for up to five years, dropping to 12 months if the sponsor stops supplying the required ongoing data. It sits outside the BPSS-first rule because some checks are carried out by the employer or airport operator.
Counter Terrorist Check (CTC) / Level 1B
CTC is for posts that involve proximity to public figures at particular risk, access to material of value to terrorists, or unescorted access to sites assessed as being at risk of terrorist attack. On top of BPSS, it adds a security questionnaire, a records check, checks of spent and unspent criminal records, and a check of Security Service records. An interview is only used if there are unresolved concerns. Cabinet Office policy is that a CTC is reviewed at least every 10 years, or every 5 years for some non-Facility-Security-Clearance contractors.
Security Check (SC)
SC is the workhorse clearance of the defence industry. It is required for posts with long-term, frequent and uncontrolled access to SECRET assets, plus occasional supervised access to TOP SECRET. On top of BPSS it adds a security questionnaire, a records check, spent and unspent criminal record checks, a credit and financial history check, and a Security Service check. An interview is the exception rather than the rule. SC is reviewed at least every 10 years (7 for some non-FSC contractors).
Read the full breakdown in What is SC clearance and how long does it take?, or browse current SC-cleared roles.
Enhanced Security Check (eSC)
eSC sits between SC and DV. It is used only for specific, agreed roles needing more assurance than SC but not the full DV process, for example, access to SECRET codeword material or certain sensitive information systems. It adds a financial questionnaire, an internet questionnaire, and a detailed interview with a trained investigating officer on top of the SC checks.
Developed Vetting (DV)
DV is the highest level commonly used in the UK and is required for frequent, uncontrolled access to TOP SECRET assets or codeword material. It carries every SC check plus a full review of personal finances, a detailed personal interview, and interviews with your referees. Cabinet Office policy is that DV is reviewed at least every 7 years. Because it is so thorough, it takes far longer to obtain than SC.
See What is DV clearance? for the full process and timelines, or browse DV-cleared roles.
Enhanced Developed Vetting (eDV)
eDV is required for a very small number of agreed posts needing assurance above DV. It can only be requested by a limited set of sponsors with prior agreement from UKSV and the Cabinet Office, and adds family, travel and additional interview elements to the DV process.
Common questions
Can I apply for clearance myself? No. You must be sponsored by an employer for a role that needs it, and the sponsoring organisation owns and maintains the clearance.
Is clearance transferable between jobs? Not automatically. A clearance can sometimes be transferred or revalidated when you move, but a new employer may need to re-sponsor or refresh it, and a long gap in cleared work can mean starting again.
Does a criminal record or debt rule me out? Not automatically. Each case is assessed individually; serious convictions, significant financial difficulty, or providing false information are the most common causes of concern. Honesty throughout the process matters more than a perfect record.
Do I need to be a British citizen? Not for every level — but residency and nationality affect eligibility, and individual roles often add their own requirements. See Do you need security clearance to work in defence?.
Where to go next
- What is SC clearance and how long does it take?
- What is DV clearance?
- Do you need security clearance to work in defence?
- Browse roles by clearance level: SC · DV
Authoritative source: United Kingdom Security Vetting, “National security vetting: clearance levels” (gov.uk). Clearance requirements are set by the department or employer responsible for each post; always confirm specifics with the hiring organisation.