Many service members leave the military planning to use their security clearance to help them find a civilian job in the defense industry. But not all security clearances are created equally, and not every military job requires a security clearance. In upcoming weeks we’ll review military occupation specialties (jobs) from each military branch which require holding a security clearance. If you’re considering joining the military, it’s helpful to consider what the security clearance requirements may be.

Types of clearances

Within the Department of Defense, there are three main levels of clearances. They are coded by the level of damage that an unauthorized disclosure of information could do to the security of the United States. The levels are:

  • Confidential (C) – Some damage to national security
  • Secret (S) – Serious damage to national security
  • Top Secret (TS) – Grave damage to national security

There are two different acronyms associated with a Top Secret security clearance – Single Scope Background Investigation (SSBI) and Sensitive Compartmented Information (SCI).


An SSBI refers to the type of background investigation required for a Top Secret, SCI, or Level Q security clearance (for Department of Energy security clearance holders). The eligibility criteria are the same but a more through type of investigation is required. This includes research into employment, education, organization affiliations and checks with local police agencies where the applicant lived, worked and went to school. It can also can require a background check on the applicant’s spouse or significant other. An approved SSBI is required before one can hold an SCI.


An SCI is part of an access control system when the subject must access compartmental classified information that has been derived from intelligence sources or through information analysis. Once the need-to-know or have access to that level of information ceases to exist, so does the SCI designation. The SCI designation is often (and erroneously) thought to be a “higher” rating than TS, when in fact it is an access designation to a higher level of information not accessible with just a TS clearance.

Getting a clearance

There is a hierarchy of background investigations based on the level of clearance. Confidential, the lowest level requires a National Agency Check Local Check (NACLC) going back 7 years into the applicant’s past. To obtain a Secret clearance requires a NACLC plus a credit investigation all going back 10 years. To get a Top Secret requires successfully passing a SSBI.

Keeping a clearance

Getting a security clearance is one thing but keeping it can be another. A periodic reinvestigation is currently required for each security level: 15 years for Confidential, 10 years for a Secret and 5 years for a TS. While the policy was recently moved to have move Secret reinvestigations to every five years, the policy has yet to be implemented, as the government looks to work down the backlog of pending investigations.

Having a current security clearance can be a significant advantage when applying for a job after getting out of the military. Your eligibility can be reinstated for up to 2 years, assuming your investigation hasn’t expired. This not only saves an employer hiring you money, but also time.

Many veterans wonder if previously possessing a security clearance is still an advantage, even if it’s expired. It is still advantageous to list your ‘clearability,’ and having a prior clearance can be a positive when compared to a never-cleared applicant. Unfortunately, a previous clearance will not speed up or advance a new investigation, and you’ll need to wait for a new investigation just like all other new applicants. But your clearability may be a selling point for employers who are able to put you to work with an interim security clearance. Assuming no adverse issues have arisen since, your previous clearance increases your chances of obtaining an interim clearance quickly.

In the next article in this series, we look at sample of Army military jobs that require security clearances at the different levels.

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Kness retired in November 2007 as a Senior Noncommissioned Officer after serving 36 years of service with the Minnesota Army National Guard of which 32 of those years were in a full-time status along with being a traditional guardsman. Kness takes pride in being able to still help veterans, military members, and families as they struggle through veteran and dependent education issues.