- COHN-S is issued by ABOHN and requires 3,000 occupational health nursing practice hours in five years.
- The exam has 160 questions (135 scored, 25 unscored) in a 3-hour closed-book session.
- Total initial cost is $550: a $150 application fee plus a $400 examination fee.
- Clinical Practice and Case Management is the largest domain, worth 45 scored items.
What Is COHN-S Certification?
The Certified Occupational Health Nurse - Specialist (COHN-S) credential recognizes registered nurses who practice at an advanced level within occupational and environmental health. It is not an entry-level badge - it verifies that a nurse has accumulated substantial hands-on hours managing workplace injury and illness programs, regulatory compliance, and health surveillance at a scope beyond generalist practice. If you're still deciding whether this is the right credential for your career stage, our overview of what COHN-S certification means and the plain-language breakdown of what COHN-S is are good starting points before you commit to the application fee.
Because "COHN-S" is used loosely in casual conversation, it's worth being precise: on this site, and throughout this article, COHN-S refers exclusively to the Certified Occupational Health Nurse - Specialist credential administered by the American Board for Occupational Health Nurses, Inc. (ABOHN). If you want the full etymology of the acronym, see COHN-S meaning and what COHN-S stands for.
Who Administers the COHN-S and How It's Delivered
ABOHN owns and governs the COHN-S credential, including eligibility standards, the exam blueprint, and recertification policy. Day-to-day test delivery is handled by Assessment Systems Corporation (ASC), which offers candidates a choice between in-person test-center appointments or live remote proctoring through MonitorEDU. That flexibility matters for occupational health nurses who may work irregular shifts at plant sites, clinics, or remote job locations and can't always travel to a fixed testing center.
Eligibility Requirements
Before you can even register, ABOHN requires three things to be true:
- A current, unrestricted RN license (or recognized international equivalent)
- A bachelor's degree or higher, in any field of study
- 3,000 hours of occupational health nursing practice completed within the preceding five years
Qualifying coursework in occupational or environmental health can offset a portion of the required practice hours, so nurses coming from a formal occupational health education track shouldn't assume they need the full 3,000 hours logged purely on the job. For a full walkthrough of how the hour credit works and how to document your eligibility packet, see our dedicated guide to COHN-S requirements.
Key Takeaway
Start logging and organizing your practice-hour documentation early - eligibility review takes time, and testing windows once approved are finite.
Exam Format and Fees
The COHN-S exam consists of 160 four-option multiple-choice questions, of which 135 are scored and 25 are unscored pretest items used to evaluate future questions. Candidates are given 3 hours to complete the exam, and it is administered closed-book. Under the 2026 candidate handbook, breaks are not permitted during the session, so pacing and physical readiness (hydration, restroom timing beforehand) become part of your exam-day strategy, not an afterthought.
Initial certification fees total $550, broken into a $150 application fee and a $400 examination fee. Once your eligibility is approved, you have a 120-day window in which to schedule and sit for the exam - miss that window and you'll need to re-establish eligibility. For a complete line-item breakdown of every fee, including recertification costs, read COHN-S certification cost. If you're mapping out when to apply relative to open testing periods, check COHN-S exam dates.
The Four COHN-S Domains
The current exam blueprint took effect September 1, 2024, following a 2023 practice analysis of what occupational health nurse specialists actually do on the job. The 135 scored questions are distributed across four domains, and the weighting tells you exactly where to concentrate your study hours.
Domain 1: Clinical Practice and Case Management (45 scored items)
The largest domain by a wide margin, covering direct clinical assessment, injury and illness case management, and treatment/referral decision-making in the occupational setting.
- Assessment and triage of work-related injuries and illnesses
- Case management coordination between employee, employer, and treating providers
- Clinical decision-making within occupational health scope of practice
Domain 2: Risk and Compliance (32 scored items)
Focuses on regulatory frameworks, hazard identification, and the compliance obligations that shape how occupational health programs operate.
- Workplace hazard recognition and risk assessment
- Regulatory and legal compliance considerations
- Exposure monitoring and recordkeeping obligations
Domain 3: Program Management and Quality Assurance (30 scored items)
Tests your ability to build, run, and continuously improve an occupational health program rather than just respond to individual cases.
- Program design and health surveillance planning
- Quality assurance and outcomes measurement
- Data collection and program evaluation methods
Domain 4: Operations and Business Management (28 scored items)
Covers the administrative and business side of occupational health nursing - budgeting, staffing, vendor coordination, and organizational operations.
- Budget and resource management for health programs
- Staffing, supervision, and interdisciplinary coordination
- Vendor and stakeholder communication
Because these four domains carry different weights, an even split of study time across all of them wastes effort. For a deeper breakdown of subtopics tested within each domain, see the full COHN-S exam domains guide.
Passing Standard and Pass Rate
ABOHN sets the COHN-S passing standard using an Angoff-based criterion-referenced method. In practice, this means the passing score is determined by expert judgment about what a minimally competent COHN-S candidate should know on each item, rather than being curved against other test-takers. That distinction matters: you are not competing against the room, you are being measured against a fixed competency bar. For the mechanics of how that scaled score is calculated, see COHN-S passing score.
ABOHN's most recently reported result was for the 2025 COHN-S cohort: 94 of 113 examinees passed, an 83% pass rate. That figure describes a specific annual group of candidates and is not a guarantee of any individual's outcome, but it does indicate that well-prepared candidates pass at a solid rate. A closer look at how this number has trended, and what it implies about exam difficulty, is available in our COHN-S pass rate analysis and the broader how hard is the COHN-S exam difficulty guide.
| Exam Detail | Specification |
|---|---|
| Total questions | 160 (135 scored, 25 unscored) |
| Time limit | 3 hours, closed-book, no breaks |
| Format | Four-option multiple choice |
| Passing standard | Angoff-based criterion-referenced |
| 2025 reported pass rate | 83% (94 of 113 examinees) |
| Total initial fees | $550 ($150 application + $400 exam) |
| Eligibility window to test | 120 days after approval |
Who Hires COHN-S Nurses
COHN-S holders typically work in roles where the scope goes beyond basic case management into program oversight - think corporate occupational health departments at manufacturing and industrial employers, health system occupational medicine divisions, insurance and workers' compensation carriers, and consulting firms that design workplace health programs. Employers value the credential because it signals hands-on hours plus mastery of the same four domains tested on the exam: clinical case management, regulatory risk, program quality, and operational management. If you're evaluating career paths or job postings that reference the credential, browse COHN-S jobs and the earnings analysis in COHN-S salary guide. For a candid look at whether the investment of time and fees pays off relative to your career goals, read is the COHN-S certification worth it.
Recertification Cycle
COHN-S certification is not permanent - it operates on a five-year recertification cycle. To maintain the credential, certificants must pay $150 annually, hold a current unrestricted RN license, complete 50 occupational health nursing continuing-education hours, and maintain 3,000 occupational health nursing practice hours. This ongoing requirement reinforces that COHN-S is meant to reflect current, active practice rather than a one-time exam pass sitting on a resume.
Building a Domain-Weighted Study Plan
Given that Clinical Practice and Case Management alone accounts for 45 of the 135 scored items - nearly a third of the exam - your study calendar should mirror that weighting rather than treat all four domains equally. A reasonable approach is to open your prep with the heaviest domain, build toward the mid-weight domains, and finish with focused review and full timed practice sessions that respect the no-break, 3-hour format.
Clinical Practice and Case Management
- Review injury/illness assessment and triage protocols
- Work through case management scenario questions
Risk and Compliance
- Study hazard recognition and exposure monitoring rules
- Drill recordkeeping and regulatory compliance scenarios
Program Management and Quality Assurance
- Review program design and outcomes measurement concepts
- Practice data-interpretation style questions
Operations and Business Management
- Cover budgeting, staffing, and vendor coordination topics
Full Review and Timed Practice
- Take full-length, no-break timed practice exams
- Revisit weak domains flagged by practice results
For a more detailed week-by-week methodology, including how to convert practice-test scores into a targeted review list, see the COHN-S study guide. And if you want a fast-reference summary of key facts to review the night before your exam, bookmark the COHN-S cheat sheet.
Whatever schedule you build, the most reliable way to gauge readiness is repeated exposure to exam-style questions under real time pressure. You can start running timed, domain-weighted practice questions on our COHN-S practice test platform to see where your scores stand relative to each of the four domains before you commit to a test date.
Frequently Asked Questions
Candidates need a current unrestricted RN license (or international equivalent), a bachelor's degree or higher in any field, and 3,000 occupational health nursing practice hours completed within the preceding five years. Qualifying occupational/environmental health coursework can offset part of the practice-hour requirement.
Initial certification costs $550 total: a $150 application fee plus a $400 examination fee, both paid to ABOHN through the ASC-managed application process.
It's 160 four-option multiple-choice questions - 135 scored and 25 unscored - administered closed-book in a 3-hour session with no breaks permitted under the current candidate handbook.
ABOHN uses an Angoff-based criterion-referenced standard, meaning the passing bar reflects expert judgment on minimum competency for each item rather than a curve against other candidates.
COHN-S operates on a five-year recertification cycle. Maintaining it requires annual $150 payments, current RN licensure, 50 occupational health nursing continuing-education hours, and 3,000 occupational health nursing practice hours.