Key takeaways
- ISO 17100 sets requirements specific to translation services, including the resources and core processes needed for a quality translation service.
- ISO 9001 is a general quality management system standard used by more than one million organisations worldwide; it does not define how translation should be done.
- ISO/IEC 27001 defines requirements for an information security management system and matters when you send confidential documents.
- ISO does not certify organisations itself; certificates are issued by independent certification bodies and can be checked with the issuer.
- No ISO certificate guarantees a good translation of your specific text; it is evidence of controlled processes, not of individual outcomes.
This guide is for procurement teams and buyers who see ISO numbers on translation providers' websites and tender responses and need to know what each one actually proves. It compares ISO 17100 and ISO 9001, explains where ISO/IEC 27001 and ISO 18587 fit, and shows how to check that a certificate is genuine.
Certification is one of several selection criteria. The others are set out in our guide on how to choose a translation agency.
What is ISO 17100?
ISO 17100 is the international standard for translation services. The ISO catalogue entry for ISO 17100:2015 says it “provides requirements for the core processes, resources, and other aspects necessary for the delivery of a quality translation service that meets applicable specifications.”
Its best-known requirement is that a second qualified person revises each translation. The Association of Translation Companies (ATC) puts it this way in its article on the planned revision: “ISO 17100 prescribes that a second person should revise the translation to ensure quality assurance.” The standard also sets competence and qualification requirements for translators.
Two scope limits matter to buyers. The ISO entry states that “The use of raw output from machine translation plus post-editing is outside the scope of ISO 17100:2015” and that it “does not apply to interpreting services.” ISO lists the standard as due to be revised, and the ATC reports that machine translation and AI are among the topics under discussion.
What is ISO 9001?
ISO 9001 is the general standard for quality management systems, applicable to any organisation in any sector. ISO describes it as “the world's leading quality management standard, used by more than one million organizations worldwide.” The ISO catalogue entry for ISO 9001:2015 notes that this fifth edition has been withdrawn and replaced by ISO 9001:2026, and that certified organisations should consult their certification body about transition arrangements.
For a translation company, ISO 9001 means it has a documented management system: defined processes, handling of complaints and non-conformities, internal audits, management review and continual improvement. It does not prescribe translator qualifications or a revision step; those are set by the company's own procedures.
ISO 17100 vs ISO 9001 vs ISO 27001 vs ISO 18587: what is the difference?
Each standard answers a different buyer question. The table summarises what they cover.
| Standard | What it covers | Translation-specific? | Question it answers for a buyer |
|---|---|---|---|
| ISO 17100 | Translation processes, translator and reviser competence, revision by a second person | Yes | Is the translation workflow itself controlled? |
| ISO 9001 | Quality management system for the whole organisation | No | Is the company managed, audited and improved systematically? |
| ISO/IEC 27001 | Information security management system (ISMS) | No | Will my confidential files be protected? |
| ISO 18587 | Full human post-editing of machine translation output, post-editor competence | Yes | Is machine-translated content edited under a defined process? |
ISO describes ISO/IEC 27001 as “the world's best-known standard for information security management systems (ISMS)” and states: “It defines requirements an ISMS must meet.” According to the ISO Survey 2022, cited on the same page, over 70,000 ISO/IEC 27001 certificates were reported in 150 countries. ISO 18587, the post-editing standard, is explained in what machine translation post-editing (MTPE) is.
Which certification should a translation buyer ask for?
Ask for the certification that matches your main risk, rather than the longest list of logos.
- Published, regulated or high-stakes content: ask how translations are revised and by whom. ISO 17100 is one way of evidencing this; a documented revision step under ISO 9001 is another.
- Confidential, personal or commercially sensitive files: ISO/IEC 27001 and Cyber Essentials are the relevant evidence; see data security when outsourcing translation.
- Long-term programmes and framework contracts: ISO 9001 shows the provider can manage complaints, corrective actions and continual improvement.
- Machine-assisted workflows: ask whether post-editing follows ISO 18587 principles and what quality level is promised.
Whatever the certificate, also ask to see the actual process: who translates, who revises and what checks are run. The steps are explained in how translation quality assurance works.
How do you check that an ISO certificate is genuine?
ISO itself never issues certificates. Its certification page states: “ISO does not perform certification or issue certificates, and it does not permit anyone to use the ISO logo in connection with certification.” Certificates are issued by independent certification bodies, and accreditation provides independent confirmation of those bodies' competence. To check a claim:
- Ask for a copy of the certificate, not just a logo on the website.
- Check the standard and edition, the company's legal name and the certificate's expiry date.
- Read the scope statement: it should cover the services you are buying.
- Identify the certification body and check whether it is accredited.
- Verify the certificate with the certification body, or through the accreditation database that ISO's certification page points to.
Common mistakes when judging translation certifications
The most common mistake is treating any ISO logo as proof of translation quality. Others to avoid:
- Confusing ISO 9001 with ISO 17100. ISO 9001 covers management, not the translation workflow itself.
- Assuming ISO 17100 covers machine translation. Raw MT plus post-editing is outside its scope.
- Ignoring the scope statement. A certificate may cover only one office or service line.
- Accepting “compliant with” as “certified to”. Compliance claims are self-declared; certification is independently audited.
- Skipping the sample test. Certification shows a controlled process, not how well your specific content will be translated.
How TranslationWorks can help
TranslationWorks is a UK-based translation agency certified to ISO 17100 (translation services), registered to ISO 9001 (quality management) and ISO 27001 (information security), and certified under Cyber Essentials, so all three standards discussed in this guide apply to how we work. It provides professional human translation by native-speaking linguists in 150+ languages, plus transcreation, transcription, interpreting and custom language services, and has served 300+ companies. If your tender or procurement process asks for evidence of certification, mention this in your request and we will confirm what we can provide alongside your free quote. See our translation services or request a free quote within 24 hours.
