ASQ and IASSC are both accredited Lean Six Sigma certification bodies but differ significantly in approach. ASQ requires work experience at the Green and Black Belt levels, plus a completed project for Black Belt, making it experience-backed. Its exams are open book and fees run $434–$585. IASSC, on the other hand, has zero prerequisites — anyone can sit for the exam regardless of experience. However, its exams are closed book and fees are lower at $250–$450. Both follow a 3-year recertification cycle. Simply put, ASQ certifies what you’ve done and know, while IASSC certifies what you know alone.
Table of contents
Key Takeaways
- ASQ and IASSC are both accredited Lean Six Sigma certification bodies but differ significantly in requirements and exam formats.
- ASQ requires work experience and a project for certification, while IASSC has no prerequisites for exam candidates.
- Exam fees for ASQ range from $434 to $585, while IASSC fees range from $250 to $450.
- ASQ offers Master Black Belt certification, whereas IASSC does not provide this level of certification.
- Both organizations require recertification every three years, but IASSC certification is recognized perpetually without additional proof.
If you are considering a Lean Six Sigma certification, two names come up more often than any other: ASQ and IASSC.
Both are recognized certification bodies. Both offer Yellow Belt, Green Belt, and Black Belt certifications. Further, both are backed by accreditation from credible third-party bodies. And yet the two programs differ meaningfully in their eligibility requirements, exam structure, fees, recertification approach, and the philosophies behind how they assess competence.
Choosing the right certification matters. It affects how much preparation time you need, what credentials employers recognize, and whether you qualify to sit for the exam at your current career stage.
This article presents a factual, side-by-side comparison of ASQ and IASSC certifications based exclusively on information published on the official ASQ website (asq.org) and the official IASSC website (iassc.org). No third-party opinions, rankings, or salary claims are included. Every fact is directly verifiable at the source URLs cited.
Who Are ASQ and IASSC?
ASQ — American Society for Quality
ASQ (asq.org) is a global membership organization founded in 1946. It offers a broad catalog of quality-related certifications across many professional disciplines, including quality engineering, quality auditing, reliability engineering, and multiple levels of Six Sigma certification. ASQ’s Six Sigma certifications cover the Yellow Belt (CSSYB), Green Belt (CSSGB), Black Belt (CSSBB), and Master Black Belt (CMBB) levels.
ASQ’s certification programs are accredited by the ANSI National Accreditation Board (ANAB) under the ISO 17024 standard, demonstrating impartial, third-party validation that the certification program has met recognized national and international credentialing industry standards for a program’s development, implementation, and maintenance.
IASSC — International Association for Six Sigma Certification
IASSC (iassc.org) is an independent, third-party certification association focused specifically on Lean Six Sigma. It established the IASSC Lean Six Sigma Body of Knowledge (ILSSBOK) and created the IASSC Certified Black Belt (ICBB) Exam, the IASSC Certified Green Belt (ICGB) Exam, and the IASSC Certified Yellow Belt (ICYB) Exam. IASSC positions itself as an independent certifying body that is separate from any training provider.
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The Fundamental Philosophical Difference
The most important difference between ASQ and IASSC is not the exam format or the fee — it is the underlying philosophy about what a certification should measure and require.
ASQ requires demonstrated work experience and, at the Black Belt level, a completed project. Certification is tied to real-world application of the methodology.
IASSC requires only that a candidate pass a standardized knowledge exam. No work experience, no project completion, and no specific training provider are required.
There are no prerequisites required in order to sit for the IASSC Certified Lean Six Sigma Black Belt Exam.
IASSC’s reasoning for this approach is stated directly on their official position page: the ICBB, ICGB and ICYB exams require no prerequisites, no specific training from one provider or another, no specific type of training method and no “proof” of project work.
These exams are professionally developed and use psychometrics to measure a person’s knowledge of the Lean Six Sigma Methodology from a standardized testing perspective as it relates to the IASSC Lean Six Sigma Body of Knowledge.
ASQ’s position is different. Six Sigma Black Belt certification requires that you complete at least one Six Sigma project and submit a project affidavit. At the Green Belt level, ASQ requires three years of on-the-job experience in one or more of the areas of the Certified Six Sigma Green Belt Body of Knowledge.
Neither approach is objectively superior. They reflect different answers to a legitimate question: does a certification measure what someone knows, what they have done, or both?
Also Read: Best Lean Six Sigma Training in Cleveland
Certifications Offered at Each Level
Yellow Belt
ASQ — Certified Six Sigma Yellow Belt (CSSYB)
The Certified Six Sigma Yellow Belt has no experience or education requirements. The Six Sigma Yellow Belt Certification will be aimed at those new to the world of Six Sigma who have a small role, interest, or need to develop foundational knowledge. Yellow Belts can be entry level employees that seek to improve their world or executive champions who require an overview of Six Sigma and DMAIC.
Exam fee: $434 for non-members. ASQ members save $100 on the initial exam fee.
IASSC — Certified Lean Six Sigma Yellow Belt (ICYB)
The IASSC Certified Lean Six Sigma Yellow Belt (ICYB) is a professional who is well versed in the foundational elements of the Lean Six Sigma Methodology, who leads limited improvement projects and/or serves as a team member as a part of more complex improvement projects led by a Certified Green Belt or Certified Black Belt, typically in a part-time role.
A Lean Six Sigma Yellow Belt possesses a thorough understanding of the elementary aspects of the Lean Six Sigma Method including competence in the subject matters contained within the phases of Define, Measure, and Control (DMC) as defined by the IASSC Lean Six Sigma Yellow Belt Body of Knowledge.
There are no prerequisites required in order to sit for the IASSC Certified Lean Six Sigma Yellow Belt Exam. Exam voucher fee: $250 USD.
Green Belt
ASQ — Certified Six Sigma Green Belt (CSSGB)
A Six Sigma Green Belt plays a critical role in quality improvement projects, working alongside or under the guidance of a Six Sigma Black Belt. This certification is ideal for professionals with at least three years of work experience who want to showcase their expertise in Six Sigma tools, data-driven problem-solving, and process optimization.
Requirement: three years of on-the-job experience in one or more of the areas of the Certified Six Sigma Green Belt Body of Knowledge. Educational waivers are not granted for this exam.
Exam fee: $483 for non-members. ASQ members save $100 on the initial exam fee.
IASSC — Certified Lean Six Sigma Green Belt (ICGB)
The IASSC Certified Lean Six Sigma Green Belt (ICGB) is a professional who is well versed in the core to advanced elements of Lean Six Sigma Methodology, who leads improvement projects and/or serves as a team member as a part of more complex improvement projects led by a Certified Black Belt, typically in a part-time role. A Lean Six Sigma Green Belt possesses a thorough understanding of all aspects of the Lean Six Sigma Method including competence in subject matters contained within the phases of Define, Measure, Analyze, Improve and Control (DMAIC) as defined by the IASSC Lean Six Sigma Green Belt Body of Knowledge.
There are no prerequisites required in order to sit for the IASSC Certified Lean Six Sigma Green Belt Exam. Exam voucher fee: $350 USD.
Black Belt
ASQ — Certified Six Sigma Black Belt (CSSBB)
The Six Sigma Black Belt Certification is designed for professionals aiming to lead quality improvement initiatives and drive organizational excellence. As a Black Belt, you’ll master Six Sigma philosophies and principles, including the DMAIC model, and develop team leadership skills to effectively manage projects.
Requirements: three years of on-the-job experience in one or more of the areas of the CSSBB Body of Knowledge, and one completed project with signed affidavit, or two completed projects with signed affidavits. Candidates must have worked in a full-time, paid role.
Exam fee: $585 for non-members. Retake fee: $385. ASQ members save $100 on the initial exam fee.
IASSC — Certified Lean Six Sigma Black Belt (ICBB)
The IASSC Certified Lean Six Sigma Black Belt (ICBB) is a professional who is well versed in the Lean Six Sigma Methodology, who leads complex improvement projects, typically in a full-time capacity.
A Lean Six Sigma Black Belt possesses a thorough understanding of all aspects of the Lean Six Sigma Method including a high-level of competence in the subject matters contained within the phases of Define, Measure, Analyze, Improve and Control (DMAIC) as defined by the IASSC Lean Six Sigma Black Belt Body of Knowledge. A Lean Six Sigma Black Belt understands how to implement, perform, interpret and apply Lean Six Sigma at an advanced level of proficiency.
There are no prerequisites required in order to sit for the IASSC Certified Lean Six Sigma Black Belt Exam. Exam voucher fee: $450 USD.
Master Black Belt
ASQ — Certified Master Black Belt (CMBB)
The ASQ Master Black Belt (MBB) certification is a mark of career excellence and aimed at individuals who possess exceptional expertise and knowledge of current industry practice. Master Black Belts have outstanding leadership ability, are innovative, and demonstrate a strong commitment to the practice and advancement of quality and improvement.
To be eligible to apply for the MBB examination, a candidate must hold a current ASQ Six Sigma Black Belt certification (CSSBB) and pass the MBB portfolio review process.
IASSC does not offer a Master Black Belt certification. This level is exclusive to ASQ among the two bodies covered in this article.
Exam Format Comparison
ASQ Exam Structure
Yellow Belt (CSSYB): Computer-delivered, multiple-choice. Open book — candidates may bring their own reference materials.
Green Belt (CSSGB): Computer-delivered, one-part, 110-question exam offered in English only. 100 questions are scored and 10 are unscored. Open book.
Black Belt (CSSBB): Computer-delivered, one-part, 165-question exam offered in English only. 150 questions are scored and 15 are unscored. Total appointment time is four-and-a-half hours; exam time is 4 hours and 18 minutes. A paper-and-pencil option is available in Mandarin at certain locations. All ASQ examinations are open book.
IASSC Exam Structure
Yellow Belt (ICYB): A 60-question, closed book, proctored exam with a 2-hour allotted time. Some forms of this exam may also include up to an additional 6 non-graded questions. The exam contains multiple-choice and true/false questions from each section of the IASSC Lean Six Sigma Yellow Belt Body of Knowledge and is administered in more than 8,000 testing centers located within 165 countries throughout the world and through the PeopleCert Online Proctoring testing system and by hundreds of IASSC Accredited Providers.
Green Belt (ICGB): A 100-question, closed book, proctored exam with a 3-hour allotted time. Some forms of this exam may also include up to an additional 10 non-graded questions. The exam contains approximately 20 multiple-choice and true/false questions from each major section of the IASSC Lean Six Sigma Green Belt Body of Knowledge.
Black Belt (ICBB): A 150-question, closed book, proctored exam with a 4-hour allotted time. Some forms of this exam may also include up to an additional 15 non-graded questions. The exam contains approximately 30 multiple-choice and true/false questions from each major section of the IASSC Lean Six Sigma Black Belt Body of Knowledge.
A key structural difference:
ASQ exams are open book — candidates bring their own reference materials. IASSC exams are closed book. This significantly affects how you prepare for each exam.
Passing Score
ASQ: The passing score for ASQ certification exams is not a fixed percentage — it is determined by a standard-setting process and varies by exam form. Candidates receive a score report showing whether they passed or failed and their performance by topic area.
IASSC: In order to achieve the professional designation of IASSC Certified Black Belt from the International Association for Six Sigma Certification, candidates must sit for the IASSC Certified Lean Six Sigma Black Belt Exam and achieve a minimum score of 70%. The same 70% minimum applies to the Green Belt and Yellow Belt exams.
Fees at a Glance
All fees are published on official ASQ and IASSC websites as of the date this article was verified. Fees are subject to change — always confirm current fees directly at asq.org and iassc.org before applying.
| Certification Level | ASQ Exam Fee (Non-Member) | ASQ Exam Fee (Member) | IASSC Exam Voucher |
| Yellow Belt | $434 | $334 | $250 |
| Green Belt | $483 | $383 | $350 |
| Black Belt | $585 | $485 | $450 |
| Retake (BB) | $385 | $285 | Not published as a separate retake fee |
ASQ membership fees are separate and not included above. IASSC exam vouchers are purchased through orders.iassc.org.
Recertification Requirements
ASQ Recertification
ASQ requires recertification every 3 years to stay current and certified. Candidates can recertify by journal (earning recertification units) or by exam. The recertification journal approach involves accumulating Recertification Units (RUs) through activities such as continuing education, work experience, professional development, and contributions to the quality field.
IASSC Recertification
IASSC Certification is recognized perpetually. In accordance with the IASSC Recertification Policy, effective March 1, 2017, a classification system recognizes certifications as “Current” for a period of three years and defines regulations for maintaining such Status.
Both bodies use a three-year cycle for maintaining “current” status, though the specific requirements for maintaining that status differ. Candidates should review the full recertification requirements directly at asq.org/cert/recertification and iassc.org/six-sigma-certification/recertification/ before applying.
Also Read: Best Lean Six Sigma Training in Minneapolis
Accreditation and Third-Party Validation
Both ASQ and IASSC hold third-party accreditation, which is an important factor when evaluating the credibility of a certification.
ASQ: This certification program is accredited by the ANSI National Accreditation Board (ANAB) under the ISO 17024 standard. ISO 17024 is the internationally recognized standard for bodies operating certification of persons.
IASSC: IASSC is a member of the American National Standards Institute (ANSI) and holds accreditation from the Institute for Credentialing Excellence (ICE). Both logos are displayed on IASSC’s official website at iassc.org.
Training Requirements
ASQ does not require candidates to complete training through any specific provider before sitting for their exams. However, ASQ offers its own preparation resources including question banks, official handbooks, study guides, and preparation courses in classroom, virtual, and self-paced formats. The CSSBB and CSSGB handbooks may be used during the open-book exams.
IASSC similarly does not require training from any specific provider. For those who wish to sit for the exam it is recommended, but not required, that Lean Six Sigma training is obtained through a qualified institution, Lean Six Sigma trainer or corporate program. It is also recommended, although not required, that those sitting for the exam have some degree of real-world Lean Six Sigma work experience and project application experience.
IASSC maintains a directory of IASSC Accredited Providers — training organizations whose curricula have been reviewed against the IASSC Body of Knowledge. Using an accredited provider is recommended but not required to sit for the exam.
Six Sigma Development Solutions is an IASSC Accredited Provider. Our onsite, live virtual, and online training programs are aligned to the IASSC Lean Six Sigma Body of Knowledge, preparing candidates for the ICYB, ICGB, and ICBB examinations.
Side-by-Side Summary Table
| Feature | ASQ | IASSC |
| Full name | American Society for Quality | International Association for Six Sigma Certification |
| Certifications offered | CSSYB, CSSGB, CSSBB, CMBB | ICYB, ICGB, ICBB |
| Master Black Belt | Yes (CMBB) | No |
| Work experience required | Yes (GB and BB levels) | No |
| Project required | Yes (BB level: 1–2 projects with affidavit) | No |
| Exam format | Open book, multiple choice | Closed book, multiple choice and true/false |
| Passing score | Set by standard-setting process | 70% minimum |
| Yellow Belt exam fee (non-member) | $434 | $250 |
| Green Belt exam fee (non-member) | $483 | $350 |
| Black Belt exam fee (non-member) | $585 | $450 |
| Recertification cycle | Every 3 years | Every 3 years (Current status) |
| Third-party accreditation | ANAB / ISO 17024 | ANSI, ICE |
| Testing locations | Prometric centers + online | 8,000+ centers in 165 countries + PeopleCert online |
All fees are as published on official websites and are subject to change. Verify current fees at asq.org and iassc.org before applying.
Important Note on Scope
This article covers only the ASQ and IASSC certification programs, as requested. It does not evaluate, compare, or comment on other Six Sigma certification bodies, training providers, or certification programs. No claim is made that either ASQ or IASSC is superior to the other, or superior to any other certification program. Both are established, accredited organizations with distinct approaches to measuring Lean Six Sigma competence.
For questions about which certification is right for your specific career goals, industry, or employer requirements, we recommend consulting directly with ASQ (asq.org) and IASSC (iassc.org), reviewing your employer’s or industry’s stated preferences, and speaking with a qualified Lean Six Sigma training advisor.
Prepare for Your Certification with Six Sigma Development Solutions Inc.
Six Sigma Development Solutions offers training programs aligned to the IASSC Lean Six Sigma Body of Knowledge, preparing candidates for the ICYB, ICGB, and ICBB exams. Our programs are available in three formats to fit your schedule:
- Onsite training at your facility, with instruction tailored to your industry and processes
- Live virtual classroom with a live instructor, real-time Q&A, and structured exercises
- Online self-paced certification you can complete on your own schedule
About Six Sigma Development Solutions, Inc.
Six Sigma Development Solutions, Inc. offers onsite, public, and virtual Lean Six Sigma certification training. We are an Accredited Training Organization by the IASSC (International Association of Six Sigma Certification). We offer Lean Six Sigma Green Belt, Black Belt, and Yellow Belt, as well as LEAN certifications.
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