COS-C Exam Preparation – Testing

• Arrive 30 minutes early. Candidates must be signed in and seated 15 minutes before the exam begins. Late arrival may reduce the available 2.5-hour testing time.
• Bring two forms of identification, including one valid government-issued ID.
• The exam is open book and open notes. Candidates may bring any paper-based OASIS reference materials, including CMS OASIS documents, the OASIS Guidance Manual, CMS OASIS Q&As, the Blueprint for OASIS Accuracy handout, and the INSTANT OASIS Answers book. Handwritten notes, loose notes, tabs, and page flags are permitted.
• Electronic devices are not permitted during testing, either inside or outside the exam room. Cell phones must be turned off.
• For paper-and-pencil exams, beverages are permitted at the candidate’s own risk. No additional testing time is provided for spills or cleanup. For computer-based testing (CBT), beverages are not permitted in the testing room.
• Food is not permitted in the exam room except when medically necessary.

General Guidance

• Exam content is based on current CMS OASIS data collection rules and guidance. Visit our Resources page for current reference materials.
• The COS-C Exam pass rate for 2025 was 78%, meaning 78 out of every 100 candidates achieved a passing score.
• Independent study of current CMS OASIS rules and guidance is encouraged but not required.
• Successful candidates should understand the intent of each OASIS item and be familiar with the Response-Specific Instructions, Coding Tips in Chapter 3 of the OASIS Guidance Manual, and related CMS Q&As.
• Exam questions may test knowledge of a specific OASIS item or present a scenario requiring candidates to apply CMS guidance and select the single correct response. All information needed to answer scenario-based questions will be provided.
• Because the exam is open book, candidates may consult their reference materials as time allows.
• Use the domain descriptions and sample questions below to guide your exam review and preparation.

The COS-C Exam tests on current CMS guidance related to OASIS regulations, data collection time points, patient populations, data collection conventions, and OASIS item-by-item guidance.

The OASIS guidance concepts covered in the exam are broken into 10 domains with the number of questions from each domain directly proportionate to the actual number of items in the OASIS data set. Broken down into percentages, exam takers can expect to see anywhere between the low and high number of questions in the exam for each domain.

The Domains covered in the exam are:

This Domain tests your knowledge of situations and events which trigger mandatory OASIS data collection as well as knowledge regarding which patients require OASIS data collection.

You will need to understand when OASIS data for Start of Care, Resumption of Care, Recertification, Other Follow-up, Transfer, Death at Home and Discharge is required to be collected. A good understanding of Time Points means that you not only can identify specific situations when OASIS data must be collected but can also discern when OASIS data collection would not be required.

You could be presented with scenarios that include information such as the patient’s age, payer, discharging facility, services ordered, events occurring during or following the clinician’s visit and be required to apply the CMS guidance to determine if OASIS data collection would be required.

This domain tests your knowledge of CMS OASIS guidance for coding items related to patient characteristics, demographics, and administrative information.

You should be familiar with the guidance for items such as A1005 – Ethnicity, M0090 – Date Assessment Completed, and M1100 – Patient Living Situation.

This domain tests your knowledge of CMS regulations governing OASIS data collection, with an emphasis on the Conditions of Participation at §484.55, Comprehensive Assessment of Patients. You should have a working knowledge of the standards addressing the initial assessment visit, comprehensive assessment, drug regimen review, updates to the comprehensive assessment, and incorporation of OASIS data items.

You should also be able to distinguish federal requirements from individual agency policies when applying OASIS guidance.

This domain tests your knowledge of OASIS item-specific guidance and scoring conventions related to patient diagnoses and sensory status. You should be familiar with items addressing areas such as hearing, vision, pain, and the reporting of patient diagnoses.

This domain tests your knowledge of OASIS item-specific guidance and scoring conventions related to nutrition, elimination, and integumentary status. You should be familiar with items addressing nutrition, incontinence, UTIs, pressure ulcers (M1306–M1324), stasis ulcers (M1330–M1332), and surgical wounds (M1340–M1342).

This domain tests your knowledge of OASIS item-specific guidance and scoring conventions related to patient mood, cognition, and behavioral status. You should be familiar with items such as C0200-C0500 – BIMS, D0150 – Patient Mood Interview, and the M1700 series addressing cognitive, behavioral, and psychiatric symptoms.

This domain tests your knowledge of OASIS item-specific guidance and scoring conventions related to patient functional status, with a focus on the M1800 functional items. You should understand the conventions that apply across the M1800 series as well as the scoring considerations specific to individual items.

This domain tests your knowledge of OASIS item-specific guidance and scoring conventions related to patient medications, vaccinations, and special treatments and procedures. You should be familiar with items such as N0415 – High-Risk Drug Classes, O0110 – Special Treatments, Procedures and Programs, and M2020 – Management of Oral Medications.

This domain tests your knowledge of OASIS item-specific guidance and scoring conventions related to emergent care, inpatient admissions, discharges, and the transfer of health information.

This domain tests your knowledge of OASIS item-specific guidance and scoring conventions for the Section GG functional items, including those that assess patient self-care, mobility status, and discharge goals.