- What "Open-Book" Actually Means for the COC
- The Three Approved Manual Categories
- Annotating Your Manuals: Rules and Strategy
- Domain-by-Domain Resource Map
- A COC-Specific Study Schedule Built Around the Domains
- Practice Tests, Mock Cases, and Timed Drills
- What You Cannot Bring Into the Testing Room
- Frequently Asked Questions
- The COC is open-book: approved CPT, ICD-10-CM, and HCPCS Level II manuals are allowed; digital references are not.
- Surgery and Modifiers is the largest domain at 22%-your manual tabs and annotations there matter most.
- You have 4 hours for 100 multiple-choice questions; manual lookup must be fast, not exploratory.
- AAPC membership is required before you can register-confirm that first to avoid application delays.
What "Open-Book" Actually Means for the COC
The phrase "open-book exam" often misleads first-time COC candidates into underestimating how much preparation is required. Yes, you may bring physical coding manuals into the testing room-but the COC's 4-hour time limit for 100 multiple-choice questions leaves you an average of fewer than two and a half minutes per question. If you need to hunt for a guideline you've never practiced with, that time evaporates quickly.
The open-book format is designed to mirror the real outpatient coding environment, where coders reference authoritative sources rather than memorizing every code. What it actually tests is your clinical reasoning and your ability to apply guidelines quickly and accurately under pressure. Candidates who treat their manuals as a crutch rather than a reference tool consistently run out of time. Candidates who have practiced with their physical manuals-tabbed, annotated, and familiar-use them as a speed advantage.
Understanding this dynamic should shape every hour of your study plan. Your goal is not to memorize every code-it's to know exactly where to find what you need and to recognize the right answer when you see it. That distinction is the foundation of a sound COC resource strategy.
The Three Approved Manual Categories
AAPC specifies that COC candidates may use the following physical reference materials during the exam. These are the only resources permitted, and they must be physical, printed books-no digital versions, no laptops, no phones.
CPT Manual (Current Year Edition)
The Current Procedural Terminology manual published by the American Medical Association is your primary tool for Domains 8 and 9, which together account for 35% of the exam. For outpatient facility coding, CPT knowledge extends into surgical packages, global periods, add-on codes, and the correct application of modifiers. The Surgery section alone-which maps directly to the exam's largest domain-spans the bulk of the CPT book. Candidates should use the current edition that aligns with the exam year they are testing in; AAPC updates its approved materials list annually, so verify the correct edition on the AAPC website before purchasing.
Tabs and highlighters are permitted inside your CPT manual. Many experienced candidates create a modifier quick-reference section, since modifier usage appears throughout multiple domains and accounts for a significant portion of Surgery and Modifiers questions.
ICD-10-CM Manual (Current Year Edition)
ICD-10-CM is the primary diagnosis coding system used across outpatient facilities, and Domain 6 dedicates 15% of the exam to it. But ICD-10-CM knowledge bleeds into several other domains as well-accurate diagnosis coding is fundamental to compliance (Domain 5), payment methodologies (Domain 4), and the case-based questions in Domain 10. Your ICD-10-CM manual should include the official guidelines, which are typically printed at the front of commercially available editions. Those guidelines are testable content.
Domain 6: ICD-10-CM (15%)
The second-largest single coding domain on the COC exam. Candidates must demonstrate mastery of outpatient-specific coding guidelines, which differ meaningfully from inpatient rules.
- First-listed diagnosis vs. principal diagnosis distinction
- Signs and symptoms coding in the outpatient setting
- Coding for encounters, screenings, and preventive care
- Combination codes, sequencing rules, and instructional notes
HCPCS Level II Manual (Current Year Edition)
HCPCS Level II codes are essential in the outpatient and ambulatory surgery center environment. Domain 7 covers HCPCS Level II at 7% of the exam, but these codes also interact with payment methodology questions and facility billing scenarios. Your HCPCS manual should be a current-year edition; codes in this system are updated quarterly by CMS, and the version available for purchase at the start of the exam year is the one you should train with.
HCPCS Level II is frequently the manual candidates are least comfortable with because it receives less emphasis in general coding curricula. Outpatient and ASC coders use it daily, which is part of why the COC specifically tests it-and part of why targeted practice with this manual pays dividends.
| Manual | Primary Domains Covered | Exam Weight (Combined) | Key Content Areas |
|---|---|---|---|
| CPT (current year) | Domain 8: CPT (13%), Domain 9: Surgery and Modifiers (22%) | 35% | Surgical packages, modifiers, E/M codes, add-ons |
| ICD-10-CM (current year) | Domain 6: ICD-10-CM (15%), Domain 10: Cases (10%) | 25%+ | Outpatient guidelines, sequencing, combination codes |
| HCPCS Level II (current year) | Domain 7: HCPCS Level II (7%), Domain 4: Payment (13%) | 20%+ | Drugs, DME, facility-specific codes, modifiers |
Annotating Your Manuals: Rules and Strategy
AAPC permits annotations-handwritten notes, tabs, highlighting, and sticky notes-inside your approved manuals. This is one of the most powerful advantages available to a well-prepared candidate. However, there are limits: pre-printed tabs sold commercially are generally acceptable, but any annotations must be handwritten by you (no photocopied or printed inserts of substantial additional content). Confirm the current annotation policy directly with AAPC before your exam date, as testing policies are subject to update.
High-Value Annotation Zones
- CPT Modifiers Appendix: Tab this and write concise outpatient-specific usage notes. Modifier -25, -59, -91, and facility-relevant modifiers appear frequently in Surgery and Modifiers questions.
- ICD-10-CM Official Guidelines: Highlight the outpatient-specific sections (Section IV) in a distinct color. These guidelines are directly tested and easy to overlook in a large manual.
- HCPCS Appendices: Tab the modifier appendix and note which modifiers are applicable to ASC and facility contexts.
- CPT Surgery Subsections: Tab major subsections (Musculoskeletal, Cardiovascular, Digestive, etc.) so you can navigate quickly during timed case questions.
Key Takeaway
Your physical manuals are the only reference tools you'll have during the COC exam. Every tab, highlight, and handwritten note you add during study becomes a time-saving navigation tool worth seconds per question-and seconds add up across 100 questions in 4 hours.
Domain-by-Domain Resource Map
The ten COC exam domains are not equal in weight, and your resource allocation should reflect that. Below is a breakdown of what each domain demands from your study materials and how to approach each one as you prepare.
Domain 9: Surgery and Modifiers (22%) - Your Highest-Priority Domain
No other domain carries more weight on the COC exam. Questions here test your ability to select correct CPT surgery codes, apply modifiers accurately in an outpatient or ASC context, and navigate surgical package rules.
- Master the global surgical package concept and what is/isn't included
- Know modifier pairs: -59 vs. -XE/XS/XP/XU, -25 with E/M on procedure day, -50 bilateral procedures
- Understand unbundling rules and CCI edits conceptually
- Practice facility vs. professional fee modifier distinctions
Domain 4: Payment Methodologies (13%) - The COC's Most Distinctive Domain
This domain is what truly differentiates the COC from other AAPC credentials. Outpatient facility coders must understand how payment systems function because code selection directly affects reimbursement.
- Ambulatory Payment Classifications (APCs) and how they apply in the hospital outpatient setting
- ASC payment system structure and covered procedures
- Medicare outpatient prospective payment system (OPPS) fundamentals
- Revenue codes and their relationship to HCPCS/CPT coding
Domain 10: Cases (10%) - Where All Skills Converge
Case-based questions present an operative note, encounter documentation, or clinical scenario and ask you to select correct codes across multiple code sets. These are the most time-intensive questions on the exam.
- Practice reading operative reports and identifying billable services
- Work through cases requiring CPT + ICD-10-CM + modifier assignments together
- Review outpatient facility coding conventions that differ from physician coding
Domains 1 (Medical Terminology, 7%), 2 (Anatomy, 7%), 3 (Coding Guidelines, 3%), and 5 (Compliance, 3%) collectively account for 20% of the exam. These are knowledge-based domains where foundational study-not manual lookup-is your primary tool. A solid anatomy and terminology review is especially valuable because understanding the body systems underlying the Surgery section makes CPT navigation faster and more accurate.
A COC-Specific Study Schedule Built Around the Domains
Rather than generic weekly templates, the schedule below is structured around the COC's actual domain weights. Spend the most time where the exam spends the most points.
Foundations: Terminology, Anatomy, and Guidelines
- Review medical terminology and body system anatomy (Domains 1 and 2, 14% combined)
- Read ICD-10-CM Official Guidelines Sections I and IV-mark key outpatient distinctions
- Begin tabbing and annotating your three physical manuals
ICD-10-CM Depth and HCPCS Level II
- Work through ICD-10-CM outpatient coding scenarios (Domain 6, 15%)
- Study HCPCS Level II code categories relevant to facility billing (Domain 7, 7%)
- Introduce payment methodology concepts: APCs, OPPS, ASC system (Domain 4, 13%)
CPT and Surgery - Maximum Effort Phase
- Systematic CPT review by body system (Domain 8, 13%)
- Intensive Surgery and Modifiers work-this is your 22% domain and deserves the most hours
- Practice modifier application in outpatient and ASC scenarios daily
- Begin timed single-domain drills using COC Exam Prep practice tests
Cases, Compliance, and Full-Length Practice
- Work through complete outpatient coding cases (Domain 10, 10%)
- Review compliance topics: OIG, CCI edits, documentation requirements (Domain 5, 3%)
- Take at least two full-length timed practice exams using physical manuals
- Identify weak domains and schedule targeted review sessions
Final Review and Manual Confidence
- Light review of all domains-no new content introduction
- Confirm your exam registration details; review the COC Exam Registration Steps and Application Guide 2026 to verify your testing logistics
- Practice physical manual navigation speed drills
Practice Tests, Mock Cases, and Timed Drills
No study material is more valuable in the final weeks of COC preparation than realistic, timed practice questions. The COC's 100-question, 4-hour format means you must develop exam stamina alongside content knowledge. Practice questions serve three functions: they reveal domain gaps, they train your pace, and they familiarize you with the question style AAPC uses.
COC questions are multiple choice with four options. Many questions present a short clinical scenario-a diagnosis, a procedure description, or a documentation excerpt-and ask you to select the correct code or apply the correct guideline. The most challenging questions combine multiple code sets in a single scenario, mirroring the Domain 10 case format.
Using practice tests on COC Exam Prep throughout your study period-not just in the final week-allows you to track progress by domain. If your Surgery and Modifiers accuracy is lagging in Week 6, you have time to course-correct before exam day. If you wait until the week before to assess, you don't.
Mock cases deserve special attention. Locate or create operative report excerpts and practice assigning complete code sets-CPT procedure code, applicable modifier(s), and ICD-10-CM first-listed diagnosis-within a target time frame. This mirrors both the Domain 10 case questions and the real-world outpatient coding workflow the COC is designed to validate.
For additional context on registration timelines and how to structure your preparation window, the COC Exam Registration Steps and Application Guide 2026 outlines how far in advance candidates should schedule their exam and what to expect from AAPC's testing delivery options.
What You Cannot Bring Into the Testing Room
Knowing what is not allowed is just as important as knowing what is. The following items are prohibited during the COC exam, whether you test at an AAPC testing center or through live remote proctored delivery:
- Digital devices: Laptops, tablets, smartphones, smartwatches-any device capable of accessing the internet or electronic references is prohibited.
- Electronic coding references: No digital versions of CPT, ICD-10-CM, or HCPCS manuals, including encoder software or online reference tools.
- Printed study guides or cheat sheets: Only the three approved manual categories are permitted. Printed summaries, study guides, or flash card decks are not allowed as reference materials during the exam.
- Non-approved books: Specialty-specific coding references, payer policy manuals, or previous-year editions not matching the current exam year are not permitted.
- Loose papers inserted into manuals: While annotations within the books are permitted, inserting separate printed documents or extensive typed notes may be flagged. Check current AAPC policy before exam day.
Remote proctored delivery adds additional environmental requirements: a cleared workspace, specific camera placement, and identity verification. If you are testing remotely, review AAPC's technical requirements carefully in advance and do a system check before your scheduled exam time. A technical failure on exam day counts against your attempt.
Frequently Asked Questions
You should bring the current-year edition that aligns with the exam year you are testing in. AAPC publishes its approved resource list for each exam year on its website. Verify the exact edition before purchasing your manuals, as using a prior-year edition may cause code-selection errors on questions where codes have changed.
Commercially pre-tabbed manuals are widely used by COC candidates and are generally acceptable. The key restriction is that inserted content beyond simple tabs-such as extensive printed reference sheets tucked between pages-may not be permitted. Handwritten annotations within the book are allowed. Confirm AAPC's current annotation policy for your exam year before testing.
The COC is distinct from the CPC rather than simply harder. It requires mastery of outpatient facility and ASC coding conventions, payment methodologies like APCs and OPPS, and the interplay between facility coding rules and HCPCS Level II-content that is not the primary focus of the CPC. Candidates with professional fee coding backgrounds will need to invest dedicated time in the payment methodology and facility-specific coding domains.
The passing score for the COC exam is 70%. The exam consists of 100 multiple-choice questions, so a passing performance requires answering at least 70 questions correctly. There is no penalty for incorrect answers, so answering every question-even if uncertain-is always the right strategy.
AAPC membership is a prerequisite for registering for the COC exam-you must be an active member at the time of registration. There is no minimum duration requirement before you can register; you can join and register in close succession. For a complete walkthrough of the registration process, including membership setup and scheduling options, review the COC Exam Registration Steps and Application Guide 2026.