Security Clearances Explained: What Candidates and Employers Should Know

Justin Pearson
Sep 4, 2024
5 min read

Updated: 4 days ago

Security clearances can feel more complicated than they need to be. Part of the confusion comes from the language. People often mix together clearance levels, SCI access, polygraphs, Public Trust positions, investigations, and agency requirements as though they are all the same thing. They are not.

At the simplest level, a security clearance is a government determination that a person is eligible for access to classified national security information. That does not mean the person can see every classified document at that level. Access still depends on the position, the information involved, a need to know, and the applicable security requirements.

For candidates and Government Contractors, the practical question is usually not, “How do I go get a clearance?” It is, “What does this position require, who sponsors the process, and what does the government evaluate?”

What does FSP clearance mean?

FSP means Full-Scope Polygraph. It is not a separate security clearance level. In cleared hiring, a requirement such as TS/SCI with FSP generally indicates Top Secret eligibility, SCI access or eligibility requirements, and a full-scope polygraph requirement as defined by the agency or program. The exact access and polygraph requirements should be confirmed before recruiting begins.

You cannot simply apply for a clearance on your own

A clearance process is tied to a government position or a contractor position that requires access to classified information. A sponsoring agency or authorized organization initiates the personnel vetting process. The position determines the level of investigation and eligibility that may be required.

DCSA explains that when a position requires access to classified information or facilities, a background investigation helps determine whether the individual will receive the required eligibility. The process is connected to the position, not something a candidate purchases or obtains independently.

What the government is actually evaluating

Clearance decisions are not supposed to come down to whether someone looks perfect on paper. National security adjudication uses established guidelines and a whole-person approach. Relevant conduct, circumstances, patterns, mitigation, recency, and the total picture matter.

The Security Executive Agent publishes the national adjudicative policy framework, including SEAD 4, the National Security Adjudicative Guidelines. Areas considered can include allegiance, foreign influence, personal conduct, financial considerations, alcohol or drug involvement, criminal conduct, handling protected information, and other security-relevant behavior. The point is not that one imperfect life event automatically ends the process. The government evaluates the information in context.

The three security clearance levels

For classified national security information, the familiar clearance levels are Confidential, Secret, and Top Secret. The level corresponds to the sensitivity of the information and the potential damage that unauthorized disclosure could cause.

Confidential: unauthorized disclosure could reasonably be expected to cause damage to national security.
Secret: unauthorized disclosure could reasonably be expected to cause serious damage to national security.
Top Secret: unauthorized disclosure could reasonably be expected to cause exceptionally grave damage to national security.

One common mistake is calling TS/SCI a fourth clearance level. SCI means Sensitive Compartmented Information. It is a form of specially controlled access that can sit on top of Top Secret eligibility when the person has the required need to know and has been approved for that compartmented access.

Where polygraphs fit

A polygraph is also not a separate clearance level. Under ODNI Security Executive Agent Directive 2, the federal personnel-security framework distinguishes a Counterintelligence Scope Polygraph (CSP) from an Expanded Scope Polygraph (ESP). The same directive says ESP has also been referred to as a Full-Scope Polygraph (FSP) or Expanded-Scope Screening (ESS) examination in some organizations.

An FSP therefore describes the scope of a polygraph examination, not a fourth clearance level. SEAD-2 defines an ESP/FSP as including the counterintelligence topics covered by a CSP plus criminal conduct, drug involvement, and falsification of security questionnaires and forms. Agency and program requirements still vary, so employers should define the exact eligibility, SCI access, and polygraph requirement before sourcing begins.

Public Trust is different

Public Trust is frequently described as though it were another clearance level. It is not a national security clearance. Public Trust positions are designated according to position risk and may require background investigation and suitability or fitness determinations, but that is different from eligibility for access to classified information.

The process is becoming more continuous

The personnel vetting system has changed significantly from the old model of simply waiting for the next periodic reinvestigation. DCSA now uses Continuous Vetting to review relevant information on an ongoing basis while an individual remains in a trusted population. Automated record checks can generate alerts that are then assessed and, when needed, investigated or adjudicated.

The National Background Investigation Services, or NBIS, is also central to the modernization of federal personnel vetting. DCSA describes NBIS as the federal government's end-to-end IT system supporting initiation, application, investigation, adjudication, and continuous vetting.

What candidates should know

Be accurate and complete. Trying to hide an issue can create a different and sometimes larger concern than the original issue itself.
Know what you actually hold. Eligibility, current access, SCI indoctrination, polygraph status, and the date or status of an investigation are not interchangeable terms.
Understand that continued eligibility carries reporting responsibilities. If a life event or security concern may affect eligibility, follow the reporting guidance from your security office.

What Government Contractors should know

From a recruiting standpoint, vague clearance language wastes time. “Must be cleared” is not enough. A strong requisition should identify the required level, whether current access is required, whether SCI eligibility or indoctrination matters, whether a polygraph is required, whether reciprocity is possible, and which requirements are truly mandatory on day one.

That level of precision helps sourcing teams search the right population and helps candidates understand whether the opportunity is actually a fit. It also reduces late-stage surprises when a technically strong candidate cannot meet a program-specific access requirement.

Security clearance FAQs

Can I get a security clearance before I have a job that requires one?

Generally, no. The process is sponsored because a government or contractor position requires the eligibility or access.

Is TS/SCI a separate clearance above Top Secret?

No. Top Secret is the clearance level. SCI is a compartmented access determination layered on top of the required eligibility and need to know.

What does FSP clearance mean?

FSP means Full-Scope Polygraph. It is not a separate clearance level. ODNI's SEAD-2 describes an Expanded Scope Polygraph, also called FSP in some organizations, as covering counterintelligence topics plus criminal conduct, drug involvement, and falsification of security questionnaires and forms.

What does TS/SCI with FSP mean?

TS/SCI with FSP generally means the position requires Top Secret eligibility, SCI access or eligibility requirements, and a Full-Scope Polygraph requirement. Agency and program rules vary, so employers should define the exact requirement before sourcing candidates.

Does Public Trust mean someone has a security clearance?

No. Public Trust relates to position risk and suitability or fitness vetting. It is not eligibility for access to classified national security information.

For employers building cleared teams

The clearance requirement is only one part of the hiring problem. Government Contractors still need the right technical skills, mission fit, location, compensation, availability, and timing. In thin cleared markets, those requirements can shrink the reachable candidate pool quickly.

Mission Box Solutions supports funded roles, cleared IT and cyber hiring, key personnel, proposal talent, post-award ramp, and recruiting overflow through our Cleared Talent Solutions. If a clearance requirement is making a role unusually difficult to fill, define the exact access requirement first. That usually tells you where the real recruiting constraint begins.

Originally written by Dean Barker and Phil Tabor. Updated by Mission Box Solutions in August 2026 using current DCSA and Security Executive Agent guidance.