ISO 17100:2015 is the international standard for translation services. It is the most widely recognized quality benchmark in the professional translation industry - and the one most frequently cited by translation providers as evidence of their quality commitment.
But what does it actually mean? What does a translation company have to do to achieve certification? What does it guarantee - and what does it not guarantee? And how should you use it when evaluating a potential translation partner?
This guide answers those questions plainly, from the perspective of an organization that buys translation services rather than one that sells them.
01 · Definition
What ISO 17100 Is - and Isn't
ISO 17100:2015 is a process standard. It defines the requirements that a translation service provider must meet in how they manage and deliver translation projects. It covers translator qualifications, revision processes, project management procedures, terminology handling, and the pre- and post-production steps that surround the translation itself.
What it is
A verified set of process requirements covering translator qualifications, mandatory revision, project management, terminology handling, and the steps before and after translation itself.
What it is not
Not a guarantee of perfection
No standard can guarantee that every translation from a certified provider will be perfect - translation is a human process and human error is always possible.
Not a rating or ranking system
There is no ISO 17100 Bronze, Silver, or Gold. A provider is either certified or not.
Not a style or quality preference
ISO 17100 does not define what "good" writing looks like in any language. It defines the process by which translation is produced - not the subjective quality of the output.
What certification does guarantee is that the provider has demonstrated to an independent external auditor that their processes meet the standard's requirements - and that those processes are consistently followed across the projects they deliver.
02 · The standard
The Six Core Requirements of ISO 17100:2015
01
Requirement 1
Translator Qualifications
ISO 17100:2015 defines minimum competence requirements for the translators working on certified projects. A qualified translator must have at least one of the following:
A recognized university degree in translation
A recognized university degree in another field, combined with at least two years of documented full-time professional translation experience
At least five years of documented full-time professional translation experience
In addition, the translator must demonstrate competence in the source language - not just understanding it, but working with it professionally - the target language to native or near-native proficiency, and the subject matter of the content being translated.
What this means for buyers
You can rely on the fact that the translators assigned to your project meet a minimum professional standard. You are not receiving work from someone who simply "speaks the language" - you are receiving work from someone with documented professional competence. This eliminates the risk, common with unregulated providers, of receiving translation produced by unqualified individuals working under a professional's name.
02
Requirement 2
Reviser Qualifications
ISO 17100 requires that every translation is reviewed by a second qualified linguist - a reviser - before delivery. The reviser must meet the same qualification requirements as the translator and must be a different person from the translator who produced the work.
The reviser is not simply proofreading for typos. The revision under ISO 17100 is a bilingual review - the reviser checks the translation against the source text for:
Accuracy
Does the translation correctly convey the meaning of the source?
Completeness
Has all content been translated with nothing omitted?
Terminology consistency
Does the translation apply the agreed terminology throughout?
Register
Is the language appropriate for the document type and intended audience?
Linguistic correctness
Grammar, syntax, punctuation, and spelling in the target language
What this means for buyers
Every translation you receive from an ISO 17100-certified provider has been checked by a second qualified professional before it reaches you. You are not the first person to read it critically. The revision step is the most important single quality control mechanism in professional translation - and ISO 17100 makes it mandatory, not optional.
03
Requirement 3
Separation of Translator and Reviser
The standard explicitly requires that the translator and the reviser are different people. A translation cannot be self-revised.
This requirement exists because self-revision is demonstrably ineffective - the same cognitive patterns that produce an error in a first reading will typically produce the same error in a second reading by the same person. Independent revision by a second linguist catches errors that the translator could not see.
What this means for buyers
When a provider claims to "check" all translations but uses the same person to translate and review, they are not meeting the ISO 17100 standard - regardless of what they say about their quality process. The two-person requirement is specific, verifiable, and non-negotiable under the standard.
04
Requirement 4
Pre-Production Requirements
ISO 17100:2015 covers what must happen before translation begins. Pre-production requirements include:
Feasibility assessment
The provider must assess whether the project can be delivered to the required quality within the specified timeframe before accepting it. Accepting a project that cannot realistically be completed to standard is a process failure under ISO 17100.
Resource allocation
The right translator - with the right language competence and subject-matter expertise - must be identified and confirmed before work begins.
Client instructions
Any client-provided instructions, reference materials, glossaries, and style guides must be received, reviewed, and communicated to the translation team before work begins.
Source analysis
The source content must be reviewed for any issues that could affect translation quality - ambiguities, formatting complexity, embedded terminology - before the translator starts working.
What this means for buyers
A certified provider cannot simply receive your files and immediately assign them to the first available translator. Pre-production steps are required before translation begins. This is why a certified provider will sometimes ask questions before starting that an uncertified provider would not - the questions are part of the required process, not a sign of uncertainty.
05
Requirement 5
Post-Production Requirements
ISO 17100 also covers what must happen after revision is complete and before delivery. Post-production requirements include:
Final verification that the revision has been completed and all reviser feedback addressed
Verification that the delivered file matches the format and specification agreed with the client
Confirmation that all client instructions have been followed
What this means for buyers
Delivery under ISO 17100 is not simply sending a file when it is finished. There is a defined verification step that the project manager is required to complete before the file leaves the building. This reduces the risk of common delivery failures - wrong format, missing files, unaddressed reviser comments.
06
Requirement 6
Terminology and Reference Material Management
ISO 17100:2015 requires that client-provided terminology, glossaries, and reference materials are applied throughout a translation project - and that where consistent terminology is a client requirement, the mechanisms to enforce it are in place. In practice, this means:
Translation memories - databases of previously approved translations - must be maintained and applied to relevant projects
Client glossaries must be activated in the translation workflow, not just filed
New approved terminology arising from a project must be captured and made available for subsequent projects
What this means for buyers
Terminology consistency is not accidental under ISO 17100. It is a managed process. If you have approved terminology from previous projects, a certified provider is required to apply it - not to retranslate it from scratch each time.
03 · The limits
What ISO 17100 Does Not Cover
Understanding the limits of the standard is as important as understanding what it requires.
It does not cover interpreting
ISO 17100 applies to written translation only. Interpreting services are covered by separate standards - ISO 18841 for general interpreting and ISO 23155 for community interpreting, among others.
It does not define subject-matter quality
ISO 17100 requires that translators have subject-matter competence - but it does not define what "good" financial translation, legal translation, or medical translation looks like in specific terms. That is a matter of professional judgment.
It does not cover machine translation output
ISO 17100 covers human translation. If a provider uses machine translation with post-editing, a different standard - ISO 18587 - applies. Always clarify with a provider whether translation is human or machine-assisted.
It does not guarantee acceptance by external authorities
An ISO 17100-certified translation is not automatically accepted by courts, immigration authorities, or regulatory bodies. Acceptance depends on the requirements of the specific authority, not on the certification status of the provider.
It does not make all certified providers equal
ISO 17100 defines minimum requirements. Within those requirements, there is significant variation in the quality of translators, the depth of subject-matter expertise, the robustness of terminology management, and the responsiveness of project management. Certification is a baseline, not a ceiling.
04 · Due diligence
How to Verify ISO 17100 Certification
ISO 17100 certification is issued by accredited certification bodies - independent organizations that assess compliance with the standard and issue certificates to providers who meet its requirements.
What to ask when verifying certification:
01
"Can you provide a copy of your current ISO 17100:2015 certificate?"
A current certificate will show the name of the certified organization, the scope of certification, the issuing certification body, the date of issue, and the expiry date. Review all of these. An expired certificate is not current certification.
02
"Who is your certification body?"
The certification body should be an accredited organization - one that has itself been assessed as competent to issue certifications. Well-known bodies include TÜV NORD, TÜV SÜD, Bureau Veritas, DNV, and others. Less well-known bodies are not necessarily less credible - smaller national certification bodies are often fully accredited - but it is worth confirming accreditation status if you are uncertain.
03
"What is the scope of your certification?"
Some providers are certified for a limited scope - specific language pairs, specific document types, or specific offices. Confirm that the certification scope covers the work you need.
04
"When was your last external audit?"
ISO 17100 certification requires regular re-audit. A provider who has not been audited recently may have a certificate that is formally current but operationally out of date.
05 · Together
ISO 17100 and ISO 9001: Why Both Matter
ISO 17100 governs the translation process. ISO 9001 governs the quality management system within which that process operates.
17100 ONLY
Verified translation processes - but possibly without the organizational infrastructure (client feedback mechanisms, continuous improvement processes, documented quality objectives) to sustain those processes consistently over time.
9001 ONLY
A general quality management system - but no translation-specific process verification.
BOTH
Process-level requirements for translation embedded within an organizational quality management system. Together they create a more complete quality assurance framework than either standard alone.
When evaluating a translation partner for an ongoing relationship, look for both certifications rather than either alone.
06 · Evaluation
The Right Questions to Ask a Translation Provider About ISO 17100
"Is every translation independently revised before delivery?"
The answer should be yes, unconditionally. If the answer includes qualifications - "on request," "for longer projects," "for premium service levels" - the provider is not meeting the ISO 17100 requirement.
"Are the translator and reviser always different people?"
Yes is the only acceptable answer under ISO 17100.
"How do you ensure subject-matter qualified translators are assigned to specialist content?"
A compliant provider will be able to describe their translator selection and qualification process specifically. A vague answer about "experienced professionals" is not a process description.
"How do you apply client terminology and translation memory to new projects?"
A compliant provider will be able to describe how TM is maintained, how glossaries are applied, and how new approved terms are captured. If the answer suggests that each project starts without reference to previous work, the terminology management requirement is not being met.
"Can I see your current ISO 17100:2015 certificate?"
Any compliant, currently certified provider will provide this immediately.
07 · Summary
Summary
ISO 17100:2015 is a meaningful certification - one of the most relevant quality indicators available to buyers of professional translation services. It requires:
01Qualified translators with documented competence in both language and subject matter
02Mandatory independent revision by a second qualified linguist on every project
03Separation of translator and reviser roles
04Defined pre-production steps before translation begins
05Defined post-production verification before delivery
06Active management of client terminology and translation memory
It does not guarantee perfect translation, cover interpreting or machine translation, or make all certified providers equivalent.
Used correctly - as a baseline qualification combined with sector-specific experience evaluation - ISO 17100 certification is one of the most reliable indicators that a translation provider has the process infrastructure to deliver consistent quality over time.
08 · Our position
Business Team Translations and ISO 17100
Business Team Translations has held continuous ISO 17100 certification since the standard's introduction. Our certification is issued by Certa-Nova following independent external audit. We apply mandatory independent revision to every project, maintain client-specific translation memories and terminology databases, and assign translators with documented subject-matter expertise in the relevant domain.
Copies of our current certificates are available upon request.
Work with an ISO 17100:2015 certified provider
Every project delivered under our certified quality process - regardless of language, volume, or complexity.
