The US government uses three standard levels of security clearance: Confidential, Secret, and Top Secret. Executive Order 13526 sets these tiers according to how much harm unauthorized disclosure of the information would cause, and access at any level also requires a demonstrated “need to know” the specific material for your job. Beyond the three levels, restricted categories like Sensitive Compartmented Information (SCI) and Special Access Programs (SAPs) add tighter controls on top of a Top Secret clearance for the most sensitive intelligence and defense work.
Confidential
Confidential is the lowest tier. It covers information whose unauthorized release could reasonably be expected to cause “damage” to national security. Many administrative, logistics, and entry-level technical roles at the Department of Defense and other agencies operate at this level so employees can handle routine sensitive documents. The background check is a Tier 3 investigation, the same tier used for Secret, and it involves database checks, financial review, and verification of the applicant’s history.
Secret
Secret is the most commonly held clearance across the federal government and the defense contracting industry. It protects information whose unauthorized disclosure could cause “serious damage” to national security, a step above the plain “damage” threshold used for Confidential. People holding Secret access may work with tactical military plans, significant intelligence assessments, and sensitive diplomatic communications. The underlying investigation is also Tier 3, though the adjudicative scrutiny can run somewhat higher depending on how sensitive the position is.
Top Secret
Top Secret is the highest of the three standard levels. It applies to information whose unauthorized disclosure could cause “exceptionally grave damage” to national security. Candidates undergo a Tier 5 investigation, formerly called a Single Scope Background Investigation. That fieldwork is significantly deeper: investigators interview neighbors, former coworkers, personal references, and other people who can speak to the applicant’s character, loyalty, and reliability. Financial records get close attention, because unresolved debt or unexplained wealth can signal vulnerability to coercion.
Department of Energy Q and L Clearances
The Department of Energy runs a parallel clearance system for personnel who work with nuclear weapons data and other restricted information under the Atomic Energy Act. A “Q” clearance is equivalent to Top Secret, and an “L” clearance corresponds roughly to Secret and Confidential. Under federal reciprocity, a Q is accepted as a Top Secret by other agencies, and vice versa.
SCI, SAPs, and Other Restricted Access
Sensitive Compartmented Information and Special Access Programs are not clearance levels. They are access controls layered on top of a Top Secret clearance, and you must already hold Top Secret eligibility before you can be “read in” to any SCI compartment or SAP.
SCI typically protects intelligence sources and the methods used to gather that intelligence. SAPs guard highly advanced defense technology, covert operations, or other programs where even the program’s existence may be classified.
Some agencies require a polygraph examination before granting SCI access. The CIA, NSA, and DIA all mandate polygraphs for their personnel. Scope varies: a counterintelligence polygraph focuses narrowly on foreign intelligence threats, while a full-scope polygraph covers a wider range of personal conduct questions. Not every Top Secret position requires one, but virtually all intelligence community roles do.
How the Level Gets Assigned
You do not choose your clearance level, and you cannot apply for one on your own. A government agency, military branch, or cleared defense contractor sponsors you by offering a position that requires access to classified information at a particular level. The sponsor tells the Defense Counterintelligence and Security Agency (DCSA) which level the job requires, and the investigation is scoped accordingly. There is no application you can fill out independently, and no amount of money will buy a clearance.
The government pays for the investigation. Your sponsoring agency or military branch covers the cost, and for defense contractors, DCSA funds it directly. A contractor’s Facility Security Officer handles the administrative side, but neither the company nor the applicant pays investigation fees.
Whichever level applies, adjudicators evaluate your file against the 13 adjudicative guidelines set out in Security Executive Agent Directive 4, covering areas like foreign influence, financial considerations, criminal conduct, and drug involvement. No single guideline is automatically disqualifying. Adjudicators use a “whole-person concept,” weighing the seriousness of any concern, how recent it is, and what you have done to address it. Financial problems are the most common reason for denial or revocation, largely because they suggest vulnerability to bribery or coercion.
Interim Clearances
Because full investigations take months, agencies can grant interim clearances to keep work moving. An interim Secret or interim Top Secret is issued at the start of the investigation based on a favorable review of your SF-86, clean fingerprint results, and confirmed U.S. citizenship. Interim access lets you handle classified material at that level while the full investigation proceeds, but it can be withdrawn at any point if investigators surface derogatory information. When the full investigation and adjudication finish, a final eligibility determination replaces the interim status.
How Long Each Level Lasts
Clearances have traditionally been reinvestigated on fixed cycles tied to the level: every five years for Top Secret, every ten years for Secret, and every fifteen years for Confidential. That model is being phased out. Under the Trusted Workforce 2.0 initiative, the government is moving to continuous vetting, an automated system that monitors cleared individuals through ongoing checks of financial records, criminal databases, and other government and public data sources. Concerns that once would not have surfaced until a periodic reinvestigation years later can now trigger an immediate review.
DCSA has enrolled roughly 3.8 million cleared personnel in continuous vetting so far. Delays in the National Background Investigation Services IT system have pushed full implementation into fiscal year 2027, but the direction is set: the era of five- and ten-year reinvestigation cycles is ending, replaced by a system designed to catch problems closer to real time.
Your eligibility at whatever level you held stays on file after you leave a cleared position, though your access to classified information ends on your last day. If you return to a cleared job within 24 months, your existing eligibility can generally be reactivated without a new investigation. After a longer gap, a new investigation is typically required.