What is ISO 17100 – and why does it matter when choosing a translation company?

Most buyers evaluating translation companies face the same problem: translation quality is invisible until something goes wrong. A mistranslated legal clause, a regulatory filing rejected on terminology grounds, a marketing campaign that reads as foreign to native speakers – these failures arrive after the work is done and the invoice is paid. The question is how to reduce that risk before committing.

ISO 17100:2015 is the most reliable quality signal in the translation industry. Published by the International Organization for Standardization, it specifies the requirements for the core processes, translator qualifications, project management, and quality assurance steps that a translation service provider must meet and maintain to earn and keep certification. Unlike a marketing claim, ISO 17100 certification requires external audit by an independent certification body. It cannot be self-declared.

For any buyer procuring translation for legal, medical, regulatory, technical, or business-critical use, ISO 17100 certification is the minimum credible quality signal a provider can offer. Understanding what the standard actually requires (and what it does not cover) is the foundation for making an informed decision.

Tomedes holds ISO 17100:2015 certification alongside ISO 18587:2017 for machine translation post-editing and ISO 9001:2015 for quality management, the three certifications directly relevant to professional translation procurement. All three are independently audited and maintained.

Table of Contents

• Table of Contents

• What is ISO 17100, and who created it?

• What does ISO 17100 actually require from a translation company?

• What qualifications must translators have under ISO 17100?

• Why is the second-linguist review requirement so important?

• What does ISO 17100 not cover, and what other certifications matter?

• How is ISO 17100 certification verified and maintained?

• What is the difference between ISO 17100 and ISO 9001 for translation?

• How do you use ISO 17100 when choosing a translation company?

• Choosing a translation company that can prove its quality

• FAQs

What is ISO 17100, and who created it?

ISO 17100 is the international standard for translation services. Its full designation is ISO 17100:2015 (Translation services: Requirements for translation services) and it was published on May 1, 2015 by the International Organization for Standardization's Technical Committee ISO/TC 37.

The standard specifies what a translation service provider must do to deliver a quality translation service: what qualifications its translators must hold, what workflow the translation process must follow, how projects must be managed, how client confidentiality must be protected, and how feedback and corrections must be handled after delivery. It replaced the previous European standard EN 15038, extending its scope and introducing mandatory requirements that did not exist in the predecessor standard – most significantly, the requirement for mandatory second-linguist review on every translation.

ISO 17100 applies to human translation services. It explicitly does not cover raw machine translation output with post-editing, which is addressed by a separate standard, ISO 18587:2017. It also does not apply to interpreting services. A translation company citing ISO 17100 certification is making a specific, auditable claim about its human translation workflow – not a general quality marketing statement.

What does ISO 17100 actually require from a translation company?

The standard covers four operational areas: resources, pre-production, production, and post-production. Each area carries specific, auditable requirements that a certification body will verify.

1. Resources. The translation service provider must employ or contract translators, revisers, and project managers who meet documented qualification requirements. The company must maintain records proving those qualifications. It must also have technology infrastructure, terminology management, and data protection processes that meet the standard.

2. Pre-production. Before translation begins, the company must assess project feasibility, agree on specifications with the client, and complete all necessary project preparation – including source document analysis, terminology review, and any relevant style or glossary documentation.

3. Production. This is the most operationally significant section. ISO 17100 mandates a two-stage minimum production process: first, a qualified translator produces the translation and checks their own work; second, a separate qualified reviser (a different person from the translator) reviews the translation bilingually against the source document. This revision step is mandatory. It is not optional, not available as an upgrade, and not waivable by the client. Optional additional steps (subject-matter review by a domain specialist, and proofreading for layout and formatting) may be offered on top of this baseline.

4. Post-production. The company must have a documented process for handling client feedback and corrections, and must archive project files appropriately. Data protection requirements apply throughout, recognizing that translation often involves confidential or sensitive client content.

What qualifications must translators have under ISO 17100?

Translator qualification requirements are among the most specific provisions in ISO 17100, and among the most consequential for buyers evaluating provider quality.

Under the standard, every translator working on an ISO 17100-compliant project must meet at least one of three documented criteria: a recognized graduate degree in translation from an accredited institution of higher education; a recognized graduate degree in any other field combined with a minimum of two years of full-time professional translation experience; or five years of full-time professional translation experience in the relevant language pair and subject area.

The same qualification requirements apply to revisers, the second linguist who reviews the translation. This means both the translator and the reviewer on an ISO 17100-compliant project must be credentialed professionals. The certification body that audits the translation company will verify, through sampling, that these qualifications are documented for every translator and reviser used on in-scope projects.

This requirement has a direct practical implication for buyers: an ISO 17100-certified provider cannot legally substitute an unqualified translator on a certified project and maintain compliance. The credential requirement is not a hiring aspiration, it is an auditable condition of certification.

Why is the second-linguist review requirement so important?

The mandatory revision step (a bilingual review of the completed translation against the source document, conducted by a qualified linguist who was not the original translator) is the single most operationally significant requirement in ISO 17100. It is the provision that most directly protects translation quality for buyers.

Translation errors that a translator does not catch in their own work are caught by a second qualified pair of eyes. Terminology inconsistencies, meaning shifts, omissions, and register problems that survive the translator's self-check are identified in revision. This is not a theoretical quality improvement, it is the standard catch-mechanism that separates professional translation workflows from single-pass production.

The revision step is why ISO 17100-compliant translation costs more than a single-translator quote for the same word count. The cost reflects real work: a second credentialed linguist spending real time on the document. When a provider quotes significantly below the market rate for ISO 17100-compliant translation, the most common explanation is that the revision step is being compressed, outsourced to unqualified reviewers, or not happening at all.

"ISO 17100 does not make translation perfect. No standard can. What it does is establish a floor, a minimum set of processes and qualifications below which a certified provider cannot go. The revision requirement is the most important provision in the standard for buyers, because it means every translation that leaves a certified provider has been checked by someone who did not write it. That single step eliminates entire categories of error." – Ofer Tirosh, CEO, Tomedes

What does ISO 17100 not cover, and what other certifications matter?

ISO 17100 has explicit scope limitations that buyers should understand when evaluating providers.

• Machine translation post-editing is outside ISO 17100's scope. When a translation company uses AI translation output as a starting point and has human linguists review and correct it (a process called machine translation post-editing, or MTPE), that workflow is governed by ISO 18587:2017, not ISO 17100. A provider that claims ISO 17100 compliance for MTPE projects is either misstating the applicable standard or misunderstanding it. These are separate workflows covered by separate standards.

• ISO 17100 does not cover interpreting. Interpretation services (simultaneous, consecutive, or otherwise) fall outside the scope of this standard. Buyers procuring interpretation should ask providers about separate quality frameworks applicable to those services.

• ISO 17100 does not replace ISO 9001. ISO 9001:2015 is the general quality management standard that governs an organization's overall operational and management systems. A translation company can hold ISO 17100 for its translation workflow and ISO 9001 for its business operations simultaneously, and the two certifications are complementary. For enterprise procurement and vendor qualification purposes, ISO 9001 addresses organizational quality management more broadly, while ISO 17100 addresses translation-specific process quality.

The three certifications directly relevant to professional translation procurement are ISO 17100:2015 (translation services), ISO 18587:2017 (machine translation post-editing), and ISO 9001:2015 (quality management). Tomedes holds all three.

How is ISO 17100 certification verified and maintained?

ISO itself does not certify translation companies. ISO publishes the standard; an independent, accredited certification body conducts the audit and issues the certificate. Reputable certification bodies active in translation include TÜV SÜD, TÜV Nord, BSI, and ATC Certification, among others.

The certification process involves both remote and in-person audits. The auditor samples evidence (translator qualification records, project files, workflow documentation, client agreement templates, feedback records) against the requirements of the standard. If the provider meets all requirements, the certification is awarded. Certification is time-limited and subject to surveillance audits to confirm ongoing compliance.

For buyers, this means ISO 17100 certification can be verified: ask the provider for their certificate, the name of the issuing certification body, and the certification scope. A legitimate certificate will specify which languages and service types are within the certified scope, and it will have an expiry date. A general claim to be "ISO 17100 compliant" without an issued certificate from a named certification body is not the same as certification.

What is the difference between ISO 17100 and ISO 9001 for translation?

Both standards are relevant to translation quality but address different things. Understanding the distinction helps buyers ask the right questions when evaluating providers.

ISO 9001:2015 is a general quality management standard. It specifies how an organization should manage its processes, set quality objectives, control documentation, respond to nonconformances, and pursue continuous improvement. It applies to any organization in any industry. A translation company certified to ISO 9001 has demonstrated that its overall management systems meet international quality management standards – but ISO 9001 does not specify anything about translator qualifications, the revision step, or translation-specific workflow requirements.

ISO 17100:2015 is translation-specific. It mandates the particular processes, qualifications, and workflow steps that apply to professional human translation. It does not address organizational management systems broadly, but it does address in detail what happens at every stage of a translation project.

For translation procurement, both certifications are valuable and complementary. ISO 9001 indicates that the organization is well-managed. ISO 17100 indicates that the translation process itself meets documented professional standards.

How do you use ISO 17100 when choosing a translation company?

ISO 17100 certification is a first filter, not a complete evaluation. The following approach gives buyers the most useful information.

1. Verify the certificate, not the claim. Ask for the certificate document, the issuing body, and the certification scope. Confirm the certificate is current. A named, audited, expiry-dated certificate from a recognized certification body is the only verifiable form of this credential.

2. Check the certification scope. ISO 17100 certificates specify which language pairs and service types are within scope. A provider certified for French and German translation is not automatically certified for Chinese or Arabic under the same certificate. Ask whether your specific language pair and document type fall within the certified scope.

3. Ask about the revision workflow directly. ISO 17100 mandates a two-stage minimum: translation plus independent revision. Ask the provider to describe their revision process for your project type. A provider who cannot name the qualifications of their revisers or explain how the revision step works is not operating a compliant workflow, regardless of what their certificate says.

4. Pair ISO 17100 with sector expertise. Certification confirms process quality; it does not guarantee subject-matter depth. A provider certified to ISO 17100 and specialized in legal translation is meaningfully different from one certified to the same standard but without legal translation experience. Ask for evidence of work in your sector alongside the certification.

5. Consider ISO 18587 for AI-assisted workflows. If a project is large-volume and time-sensitive, a hybrid AI-plus-human workflow may be appropriate. In that case, ISO 18587:2017 certification (which Tomedes holds) is the relevant quality credential, confirming that the MTPE process is governed by the same standard of documented, audited quality assurance.

For legal translation services in particular, ISO 17100 certification is the non-negotiable baseline. Legal documents submitted to courts, government bodies, or counterparties in commercial transactions carry real consequences for errors. The revision step mandated by ISO 17100 is the primary error-catching mechanism for those documents.

Choosing a translation company that can prove its quality

ISO 17100:2015 is not a guarantee of perfection. It is a guarantee of process – a documented, externally audited commitment to qualified translators, mandatory second-linguist review, and professional project management on every translation project within its scope.

For buyers evaluating professional translation services, ISO 17100 certification is the clearest available signal that a provider has chosen to hold themselves to an independently verified standard. It answers the fundamental question every buyer faces: how do I know this provider will produce quality work before I can see the output?

Tomedes holds ISO 17100:2015, ISO 18587:2017, and ISO 9001:2015 – all three certifications independently audited and currently maintained. Every translation project is assigned a dedicated project manager and is backed by a 1-Year Quality Guarantee.

Request a free quote and ask Tomedes about the certification scope relevant to your project.

FAQs

Q: Is ISO 17100 the same as "certified translation"?
A: No, these are different things. ISO 17100 is a quality management standard for translation service providers. Certified translation refers to a translated document accompanied by a signed statement from the translator or translation company attesting that it is complete and accurate. ISO 17100 certification applies to the provider; certified translation is a deliverable format. A provider can be ISO 17100 certified and also offer certified translations, but these are separate concepts.

Q: Does ISO 17100 apply to machine translation?
A: No. ISO 17100:2015 explicitly excludes raw machine translation output with post-editing from its scope. Machine translation post-editing is governed by the separate standard ISO 18587:2017. A provider using AI translation in its workflow should be asked specifically whether that workflow is covered under ISO 18587 certification, not ISO 17100.

Q: Can a freelance translator be ISO 17100 certified?
A: ISO 17100 applies to translation service providers, which can include individual translators operating as a business. A freelance translator can in principle seek ISO 17100 certification if they maintain all required processes, documentation, and qualified resources, including access to a qualified reviser separate from themselves. In practice, most ISO 17100 certificates are held by translation agencies and companies with the infrastructure to support the full workflow and audit requirements.

Q: Is ISO 17100 mandatory for translation companies?
A: No, ISO 17100 certification is entirely voluntary. No law requires translation companies to be certified to this standard. This is precisely what makes it a meaningful signal: it represents a deliberate, costly, external-audited commitment to quality that a provider chooses to make. A translation company that has not pursued ISO 17100 certification has made a different choice – whether from cost considerations, lack of awareness, or an unwillingness to submit their workflow to external audit.

Q: How do I verify that a translation company's ISO 17100 certificate is genuine?
A: Request the certificate document directly and check: the issuing certification body's name (should be a recognized, accredited body), the certification scope (languages and service types covered), and the certificate validity dates. You can also contact the issuing certification body directly to confirm the certificate is active. A genuine certificate will have a specific scope (not a blanket claim across all languages and services) and will be issued by a named third party, not the translation company itself.