Investigation tiers vs. clearance levels: what T1, T3, and T5 actually mean

Ask someone what clearance they hold and they'll say "Secret" or "TS/SCI." Ask what investigation they're on and you'll often get a blank look, or the wrong answer. The two are related, but they are not the same thing, and the gap between them causes a surprising amount of confusion at hiring time.

For a person with a clearance, the level describes the classified information they may be eligible to access: Confidential, Secret, Top Secret. The investigation tier describes the scope of the background check used to support a vetting determination: Tier 1 through Tier 5. One is about the information. The other is about the vetting that got you there. This is the plain-English version of how the tiers work, which tier maps to which clearance, and why "Tier 4" is not more sensitive than "Tier 3" even though the number is bigger.

This is general, factual information for people working in or entering cleared roles. It is not legal, security, or career advice. Position sensitivity, investigation scope, and eligibility are determined by federal agencies and adjudicators under official policy, and specifics change over time. For your own situation, your FSO and the official sources linked at the end are the authority.

The chain nobody explains

A clearance isn't one event. It's a chain, and each link is run by a different part of the system:

• Position sensitivity and risk. The hiring agency assesses public-trust risk and national-security sensitivity based on the duties. These are related dimensions, not mutually exclusive categories. The job drives everything downstream, not the person.
• Investigation tier. That designation sets which background investigation you get. The tier is the scope and depth of the check.
• Adjudication. For national-security eligibility, an adjudicator applies the 13 SEAD 4 guidelines and the whole-person standard. Suitability, fitness, and credentialing determinations use their applicable standards.
• Eligibility. A favorable adjudication grants eligibility at a level: Confidential, Secret, or Top Secret. This is what people call "having a clearance."
• Access. Eligibility, need-to-know, the required nondisclosure agreement, and access authorization are separate requirements. For TS/SCI, access also requires being read into specific compartments.

The investigation tier sits in the middle of that chain. It's the part most candidates can't name, even though their security office can identify the investigation requested.

The five tiers

The five-tier model comes from the Federal Investigative Standards (FIS), approved in December 2012 by the Director of National Intelligence and the Director of OPM under Executive Order 13467, and fully implemented across all tiers by 2017. It replaced a tangle of older investigation types with five tiers that serve three different purposes: HSPD-12 credentialing (physical and logical access), suitability and fitness for federal work, and national security eligibility.

None of the five tiers is a security clearance. Tier 3 can support Confidential or Secret eligibility; Tier 5 can support Top Secret or SCI eligibility. A favorable adjudication is still required. Tiers 3 and 5 also serve sensitive positions that may not require classified access. The table is a guide to the five-tier terminology still used in records and postings; Trusted Workforce 2.0 is changing federal vetting processes.

Why the numbers don't go in a straight line

This is the part that trips people up. The tiers are not a single ladder of increasing secrecy. Tier 1 serves low-risk suitability and credentialing; Tiers 2 and 4 serve non-sensitive Public Trust work. Tiers 3 and 5 are the national security track. They're interleaved by number, not by sensitivity.

So a Tier 4 investigation (high risk public trust) is, by the number, "above" a Tier 3 (Secret). But neither investigation is a clearance. Tier 3 can support a national-security eligibility determination, while Tier 4 serves high-risk, non-sensitive work. A federal financial analyst in a high-risk public trust job goes through a Tier 4 and never touches classified information. A contractor cleared to Secret goes through a Tier 3 and does. The number describes which standardized investigation you got, not how classified your work is.

Public Trust is a frequent source of confusion. "Public Trust" positions feel clearance-adjacent because they involve a background investigation and a risk designation, but a public trust determination is a suitability judgment about whether you can be trusted in the role, not an eligibility judgment about access to classified national security information. You can hold a public trust position with no security clearance at all.

The old names people still use

The FIS tiers replaced a set of older investigation types, and the legacy names are still everywhere in resumes, job postings, and recruiter shorthand. If you trained or got cleared before about 2017, you probably know your investigation by its old name:

• NACI (National Agency Check with Inquiries) is now Tier 1.
• MBI (Moderate Risk Background Investigation) is now Tier 2.
• NACLC / ANACI (the old Secret-level checks) are now Tier 3.
• BI (Background Investigation) is now Tier 4.
• SSBI (Single Scope Background Investigation) is now Tier 5.

When a job posting says "must have a current SSBI" or "NACLC required," it's using the pre-FIS vocabulary for what are now Tier 5 and Tier 3. The mapping helps interpret older records. Reciprocity depends on the applicable policy, prior investigation and adjudication, current status, and gaining position requirements; the tier alone does not decide it.

"How often do I get reinvestigated?" — the answer changed

The old rule was periodic reinvestigation on a fixed clock: roughly every five years for Top Secret, every ten years for Secret. That model is being retired.

Under Trusted Workforce 2.0, the government-wide vetting reform that began implementation in 2018, periodic reinvestigations are being replaced by Continuous Vetting (CV). Instead of a scheduled re-check every five or ten years, CV runs automated record checks against criminal, terrorism, financial, and public-records databases on an ongoing basis throughout your period of eligibility. When a check produces an alert, DCSA reviews it, decides whether it warrants further investigation, and acts on it.

DCSA uses Continuous Vetting to identify potentially relevant information between traditional investigation milestones. An alert is a lead for review, not an automatic adverse determination. The rollout and requirements vary by population and agency.

CV does not eliminate questionnaire updates or self-reporting. DCSA’s April 2026 NISP contractor guidance calls for an updated SF-86 every five years, using the Personnel Vetting Questionnaire date to determine when it is due. Your security office manages submissions and any follow-up investigation.

Do not assume CV enrollment alone guarantees continued eligibility, or that an old investigation date means your clearance has expired. Ask the security office to verify the record and any outstanding requirements.

What this means at hiring time

Three things worth getting right when you're reading a job posting or filling out a profile:

• Match the tier to the clearance, not the number. Tier 3 generally supports Secret eligibility, and Tier 5 supports Top Secret or SCI eligibility. Tiers 2 and 4 serve non-sensitive Public Trust positions; Tier 1 is the low-risk, non-sensitive investigation. None of those labels establishes that eligibility has been granted.
• Your security office determines whether prior vetting can be accepted. When you move between agencies or contracts, whether your existing investigation transfers depends on its tier and currency. A current Tier 5 can support a new TS/SCI role without a fresh investigation if reciprocity applies; a Tier 3 cannot, on its own, support a TS role.
• Public trust is not a clearance. If your only federal vetting was a Tier 2 or Tier 4 public trust investigation, that vetting alone does not establish a security clearance. Describe the determination accurately rather than labeling it Secret or Top Secret.

What this looks like inside ClearMatch

ClearMatch uses your reported clearance and experience to help find relevant roles. It does not see your investigation file, government personnel-security records, or adjudicative history.

If you are unsure what you hold, ask the security office. An SF-86 is used for national-security positions, including some sensitive positions that do not require classified access; completing it does not prove that a clearance was granted. SF-85 and SF-85P are associated with non-sensitive vetting. The form is a clue to the process, not a substitute for your eligibility determination.

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Sources: Federal Investigative Standards Short — CDSE/DCSA, DCSA — Continuous Vetting, Executive Order 13467, and Trusted Workforce 2.0 materials at performance.gov. Tier designations and reinvestigation policy are set by the federal government and change over time; for your own case, consult your FSO and the official sources above.