If your roles touch classified information, you already know the right hire has to clear more than an interview. This guide explains the security clearance levels employers encounter most often, how cleared candidates are vetted, and what hiring cleared talent actually buys you. Whether you are staffing a defense program, a cybersecurity team, or an energy contract, understanding security clearance hiring up front saves you weeks of guesswork and tens of thousands in delay costs.
What a security clearance actually is
A security clearance is a formal determination that a person is eligible to access classified national security information. It is not a certification someone earns once and carries forever like a license. It is an ongoing trust decision made by the U.S. government, tied to a specific level of access and a specific need to know.
Two things matter to an employer. First, the level of eligibility a candidate holds. Second, the status of that eligibility, meaning whether it is active, current, or expired. Both shape whether a person can start contributing on day one or whether you are looking at a months-long processing cycle.
The three security clearance levels
The U.S. government uses three classification levels, defined by the damage that unauthorized disclosure would cause to national security:
- Confidential — information whose disclosure could reasonably be expected to cause damage to national security. This is the lowest level and the least common in the contractor workforce.
- Secret — information whose disclosure could cause serious damage. Secret is by far the most widely held clearance across defense and adjacent industries.
- Top Secret (TS) — information whose disclosure could cause exceptionally grave damage. A top secret clearance carries the most rigorous vetting and the longest processing timelines.
A clearance always maps to the work. You sponsor a candidate for the level a position requires, not for the highest level they might one day reach.
What is TS/SCI, and how is it different?
This is the point that trips up the most hiring managers. SCI is not a fourth clearance level above Top Secret. SCI stands for Sensitive Compartmented Information, a category of intelligence-derived information that is walled off into specific compartments.
So when a requisition reads "TS/SCI," it means two things stacked together: the person holds Top Secret eligibility and has been formally "read in" to one or more SCI compartments. Access to SCI is granted by the intelligence element that owns the information, under the standard known as ICD 704, and it requires indoctrination into each specific compartment. A candidate can hold Top Secret without SCI. A candidate cannot hold SCI without the underlying Top Secret eligibility.
You will also see references to a polygraph (CI or full-scope) attached to some TS/SCI roles, and to Special Access Programs (SAPs), which are even more tightly controlled. These are additional gates layered on top of clearance, not separate clearance levels. If your role needs a poly, say so in the requisition; reusing an existing one is far faster than starting fresh.
How candidates get vetted: the investigation tiers
Clearances are granted after a background investigation, conducted and adjudicated for most of the Department of Defense through the Defense Counterintelligence and Security Agency (DCSA). The investigation scope is set by a tier system. For clearance purposes, two tiers matter most:
| Tier | Supports | What it covers |
|---|---|---|
| Tier 3 | Confidential / Secret | National agency checks, credit, criminal history, and record reviews over a defined look-back period. |
| Tier 5 | Top Secret / SCI | Everything in a lower tier plus expanded scope: subject and reference interviews, broader record checks, and a longer, deeper look-back. |
After the investigation, a trained adjudicator weighs the findings against the federal adjudicative guidelines, covering areas like financial conduct, foreign influence, and personal conduct, before granting or denying eligibility. The investigation gathers facts; the adjudication is the actual trust decision. A clean Tier 3 case commonly runs several months end to end, and a Tier 5 can run longer still, which is exactly why an already-cleared candidate is so valuable.
Continuous vetting has replaced the old reinvestigation cycle
It used to be that clearances were reinvestigated on a fixed schedule, every five years for Top Secret and every ten for Secret. Under the government-wide reform known as Trusted Workforce 2.0, the Defense Department has moved cleared personnel into continuous vetting. Instead of waiting years between reviews, automated checks run against criminal, financial, terrorism, and other records on an ongoing basis and flag issues as they surface. Millions of cleared personnel are already enrolled. For employers, the practical upshot is that a properly maintained clearance stays monitored in real time rather than going stale between periodic reviews.
Active vs. current: why status matters as much as level
A clearance level tells you what a person was cleared for. The status tells you whether you can use it now.
- Active — the person currently holds the clearance and is in an access position. They can work classified material right away.
- Current — the clearance is not actively in use because the person left a cleared role, but it remains reinstatable, generally if there has been no break in cleared service longer than about 24 months and no new derogatory information.
- Expired — the clearance lapsed beyond the reinstatement window, and a new investigation is typically required.
Thanks to reciprocity, federal agencies are generally expected to recognize a valid investigation and eligibility from another agency, provided it meets the scope the new role demands and there has been no disqualifying break in service. That is what makes an active or current clearance portable, and it is exactly why pre-cleared candidates are worth the premium.
Why hiring pre-cleared veterans saves time and money
Sponsoring a clearance from scratch is expensive and slow. A Tier 5 investigation can take many months, during which the seat sits empty and program work waits. Hiring someone who already holds the eligibility you need can collapse that timeline dramatically.
Transitioning servicemembers and veterans are a natural fit here. Many already hold active or current Secret or TS/SCI eligibility earned in uniform, and they bring the mission discipline that cleared environments demand. That is the core of the business case for hiring veterans into cleared roles, and it is why a focused military staffing partner can move faster than a general recruiter. At LockLeed, our vetting and placement process confirms clearance level and status before a candidate ever reaches your desk, across the industries we serve, from aerospace and defense to cybersecurity and energy.
If you have a cleared requisition to fill, talk to LockLeed about your next hire. Submit a requisition or get in touch, and we will match it to vetted, security-cleared veterans ready to start.