Your client sends an RFP. Buried in the technical requirements is “ISO 18587 compliance for all MTPE deliverables.” You’ve been running MT post-editing workflows for two years, your editors are solid, your quality is consistent - but you’ve never formally mapped your process against the standard. Now you’re wondering: how far off are you, and what does closing that gap actually take?
This article breaks down ISO 18587 - what it is, what it requires from your agency, how it differs from ISO 17100, and what’s changing in the upcoming revision expected later in 2026.
What ISO 18587 actually is (and what it isn’t)¶
ISO 18587:2017 is the international standard for full post-editing of machine translation output. Published by ISO Technical Committee 37 (Terminology and other language and content resources), it defines two things: what processes agencies need to run for MTPE projects, and what competencies post-editors must demonstrate.
The standard exists because “machine translation + human review” can mean anything. One agency’s “post-editing” is a 10-minute skim for obvious errors. Another’s is a full review against the source, terminology consistency check, and style pass. ISO 18587 draws a line: this is what full, professional-grade post-editing looks like.
What it is NOT: a general translation quality standard. It doesn’t replace ISO 17100, which governs traditional human translation workflows. It specifically addresses the MTPE process - where MT output is the starting point, not a human translator working from scratch.
Full post-editing vs light post-editing - the core distinction¶
ISO 18587 covers two service levels, and they couldn’t be more different in scope.
Full post-editing is the main subject of the standard. The goal: output that is “equivalent to a professionally produced human translation.” The post-editor reads every segment against the source, corrects all errors - mistranslations, wrong terminology, unnatural phrasing, style mismatches, cultural issues - until the result reads as if a professional translated it from scratch. A second revision step (separate qualified person) may also be required, similar to the ISO 17100 revise step.
Light post-editing targets a lower bar: the text should be “comprehensible” - meaning, not embarrassing and factually not wrong, but not polished. Style, fluency, terminology precision - not the goal. Light post-editing is described in an annex to the standard, not the main body, which signals its secondary status. Many certification bodies won’t certify specifically to light post-editing levels.
The practical implication for agencies: when a client says “post-editing,” find out which level they actually want. Billing full post-editing rates for light post-editing work - or vice versa, delivering polished quality when they just need “good enough” - is a commercial and quality management problem that ISO 18587 helps avoid by formalizing the agreement upfront.
The five competencies post-editors must have¶
This is where many agencies discover the widest gap between what they do and what the standard requires. ISO 18587 defines five core competencies for post-editors, and all five need to be documentable:
1. Translation competence - The post-editor should meet ISO 17100 requirements for translators: a recognized university degree in translation, OR a degree in another subject plus two years of translation experience, OR five years of professional translation experience. This is the same bar as for “full” human translation under ISO 17100.
2. Linguistic and textual proficiency - Advanced bilingual proficiency in source and target languages, including grammar, vocabulary, register, and cultural nuance. Not “working knowledge” - expert level.
3. MT literacy - Specifically: understanding how machine translation systems work, what types of errors they produce, why they produce them, and how to efficiently find and fix those errors. This is a separate skill from translation competence. A brilliant translator who has never worked with MT output, doesn’t understand MT error patterns, and approaches it like human translation is not ISO 18587-compliant.
4. Domain expertise - For specialized content (legal, medical, technical, financial), the post-editor needs subject matter knowledge in that domain. An experienced general translator is not automatically qualified to post-edit pharmaceutical regulatory filings.
5. Post-editing skills - The practical skill of identifying errors efficiently, making minimum necessary changes (not over-editing), meeting specified quality levels for the agreed service type (full vs light), and using related tools like CAT software and QA tools.
As ATC Certification notes, the updated revision will stress even more clearly that post-editors need translator-level linguistic skills PLUS specialized MTPE training - not one or the other.
What your agency needs to document and implement¶
ISO 18587 compliance isn’t just about having qualified people. It requires documented processes. Here’s what auditors look at:
Pre-editing assessment and MT engine selection. For each project or project type, you need a documented evaluation: is this content suitable for MT? Which MT engine is appropriate for this language pair and domain? What’s the expected output quality? This can’t be implicit - it needs to be a step in your workflow with records.
Service level agreement. Client agreements must explicitly specify: full post-editing or light post-editing? What are the quality expectations? What output format? Who is responsible for what? The standard requires this to be documented, not just discussed verbally.
Post-editor qualification records. For every post-editor working on ISO 18587-compliant projects, you need documentation of their qualifications - education, experience, relevant training - mapped against the five competencies above. This is the documentation burden that catches agencies off-guard. If your freelancer pool is large, getting qualification records for all of them takes time.
Quality management procedures. How do you verify that the post-edited output meets the agreed quality level? What’s your revision process? How do you handle errors found late in the process? These procedures need to be written down and followed consistently.
Project records. Keep records of who did what on each project: which MT engine, which post-editor, what quality check was performed, when each step was completed.
As Transpose.ch points out, content must be “semantically accurate and complete, grammatically correct, aligned with required tone and style, terminologically consistent and relevant for the domain, culturally appropriate for the target audience” - and your quality management process needs to demonstrably ensure this.
How ISO 18587 relates to ISO 17100¶
These two standards are complementary, not competing. ISO 17100 covers human translation services - from initial briefing through translation, revision, and delivery. ISO 18587 covers the specific case where machine translation generates the first draft and a human post-editor reworks it.
The key structural difference: in ISO 17100 workflows, the translator works from the source. In ISO 18587 workflows, the translator works from MT output - which changes both the skill set needed and the types of errors to watch for (MT-specific errors: hallucinations, dropped negations, wrong formality register, inconsistent proper nouns).
Many agencies now hold both certifications, and there’s a good reason: clients buying premium translation services want ISO 17100; clients buying MT-assisted translation want ISO 18587. Having both lets you serve both segments without confusion about which standard applies to which workflow.
From a certification efficiency standpoint, if you already hold ISO 17100, adding ISO 18587 in a combined audit typically saves 20-30% compared to a separate audit - because many management system requirements overlap, and auditors don’t need to verify the same infrastructure twice.
What’s changing in the 2026 revision¶
ISO 18587 is currently being revised. The revision started in October 2023, and per EUATC’s April 2025 update, final publication is expected around October 2026. Here’s what’s changing:
Clearer terminology. The 2017 version predates the widespread adoption of neural MT and LLM-based translation. The revision distinguishes more precisely between machine translation output, AI-generated content, and post-editing tasks - which matters because a lot of what agencies now do blurs these lines.
Alignment with ISO 17100. The two standards will share more terminology and competence frameworks, making it easier for agencies to apply consistent processes across human translation and MTPE workflows. The longer-term direction is toward a unified framework.
Risk-based approach. Instead of prescribing specific process steps, the revised standard is expected to define quality outcomes and let agencies determine how to achieve them - more flexibility for agencies with mature, documented quality systems.
Technology integration. The revision explicitly addresses AI-assisted tools, hybrid workflows, and human-in-the-loop processes - areas the 2017 version simply didn’t anticipate.
Practical note for agencies: if you’re planning to get certified in 2026, you’ll be certifying to the current 2017 version. The new version will require transition once published. That said, the core competence and process requirements aren’t expected to disappear - the revision adds clarity, it doesn’t dismantle the foundation.
Getting certified: what the process looks like¶
For agencies already holding ISO 17100, the path to adding ISO 18587 is relatively fast - typically 2-4 weeks from starting preparation to certificate. For agencies starting from scratch, plan for 3-6 months of preparation before the audit.
The certification process typically follows four phases:
Gap analysis (1-2 days) - An assessor evaluates your current MTPE workflows against the standard’s requirements and identifies what needs to be documented, implemented, or improved.
Documentation and implementation (varies) - You adapt your quality management system to meet the standard: write or update procedures, collect post-editor qualification records, set up project record-keeping. This is the phase where most time is spent.
Audit (1-2 days) - A remote or on-site audit where the certification body reviews post-editor qualifications, sample project records, MT engine evaluation documentation, and client agreements. They may ask post-editors to demonstrate their understanding of MT error patterns.
Certificate issuance - Valid for 3 years, with annual surveillance audits.
Certification bodies offering ISO 18587 include TÜV SÜD, ATC Certification, TranslationCert, and several national-level bodies. For agencies already ISO 17100 certified, check whether your existing certification body can handle both in a combined audit - it’s almost always cheaper and faster.
On cost: the total first-year investment for a mid-to-large agency (internal time, consultant if needed, certification fee) can reach €10,000 or more. Smaller agencies with well-organized processes and existing ISO 17100 certification will land significantly lower - but budget for internal time regardless. The documentation work is real.
The gap between “we do MTPE” and “ISO 18587 compliant” is wider than you think¶
One industry observation that keeps coming up: ISO 18587 is one of the least-understood standards in the language industry, partly because MTPE is newer, and partly because the gap between informally doing MT post-editing and formally complying with the standard is wider than most agencies expect.
The issue isn’t usually quality - agencies running serious MTPE workflows often produce good output. The issue is documentation and formalization: do you have written procedures? Do you have competence records for every post-editor? Do your client agreements explicitly specify full vs light post-editing? Do you have records of which MT engine was evaluated for which project and why?
That documentation infrastructure is what ISO 18587 audits are actually testing. The quality of your translation is evidence; the paper trail is the requirement.
Agencies that have gone through the process consistently report that the certification audit itself was less stressful than preparing for it - once the documentation is in order, the rest follows.
FAQ¶
Does ISO 18587 apply if we use AI tools like ChatGPT or Claude as part of our workflow?¶
ISO 18587:2017 was written for classical MT systems, but the 2026 revision explicitly addresses AI-generated content and LLM-based translation tools. For now, if you’re using an LLM to generate a first draft that a human post-editor then works through, the process is substantively similar to MTPE and the competence requirements apply. Your certification body can advise on how to document LLM-based workflows against the current standard.
Is ISO 18587 a mandatory certification or voluntary?¶
Voluntary - there’s no legal requirement to hold ISO 18587. However, it increasingly appears in enterprise procurement requirements, especially from clients in regulated industries (pharma, legal, financial services) who want documented evidence that MT-assisted content meets defined quality standards.
Can a freelance translator be ISO 18587 compliant?¶
ISO 18587 is primarily a process standard for organizations, not an individual certification. Individual post-editors need to demonstrate the five competencies, but the certification itself is held by the agency or LSP managing the MTPE workflow. Some training programs offer post-editor credentials, but those are not the same as ISO 18587 certification.
What’s the difference between ISO 18587 full post-editing and traditional translation under ISO 17100?¶
The deliverable quality target is the same: professional-grade output indistinguishable from human translation. The process is different: in ISO 17100, the translator starts from the source document. In ISO 18587 full post-editing, the post-editor starts from MT output and corrects it. This changes the skills needed (MT literacy becomes critical), the efficiency profile (faster on MT-friendly content, not necessarily faster on content that MT handles poorly), and the error patterns to watch for.
How long does ISO 18587 certification stay valid?¶
3 years, with annual surveillance audits in between. The surveillance audits are lighter than the initial certification audit - they verify that your documented processes are still being followed and that records are maintained, without re-examining the full system.
Should we get ISO 18587 if we already have ISO 17100?¶
If you’re actively offering MTPE services, yes - it formalizes what you’re already doing and makes it defensible to clients who ask. If you’re using MT only as an internal productivity tool and not billing it as MTPE, it’s less urgent. The combined audit efficiency (20-30% cost savings vs separate audits) makes the economics straightforward for agencies already in the ISO ecosystem.