ISO 24495-1 Explained: The Plain Language Standard and How to Apply It to Company Documents
ISO 24495-1 is the international plain language standard, published in 2023 as ISO 24495-1:2023, Plain language, Part 1: Governing principles and guidelines. It defines plain language through four principles: readers get what they need (relevant), can easily find it (findable), understand it (understandable) and use it (usable). DEMA Solutions applies these principles to company documents in several languages.
Who this guide is for
This guide is for the people asked to make company documents clearer: communication managers, legal and compliance teams, heads of technical documentation, customer service leads and owners of policies and procedures. Some want to know whether ISO 24495-1 is a requirement or something they could ask a supplier to work to; others have been told a contract or manual is “too complicated” and need a method more objective than personal taste.
The standard gives you that method. It does not tell you how many words a sentence may have; it tells you how to decide, for a specific reader and task, whether a document works.
What ISO 24495-1:2023 is, and what it is not
The standard was developed by ISO technical committee TC 37 (language and terminology) and published in June 2023. National bodies have adopted it, for example as DIN ISO 24495-1 in Germany and UNE-ISO 24495-1 in Spain.
Its starting point is a definition: a communication is in plain language when its wording, structure and design are so clear that the intended readers can easily find what they need, understand what they find and use that information. Three ideas in that sentence shape everything else. Plain language is defined by the reader, not by the text: a maintenance procedure can be plain for a service technician and impenetrable for a consumer. Plain language is about structure and design as much as words: a document with short sentences can still fail if the one thing the reader needs is on page twelve. And plain language is measured by use: the test is whether readers can act on the information.
The ISO 24495-1:2023 plain language standard applies to most written languages and to printed and digital documents that are mainly text, from public information to technical writing and legislative drafting, with examples in English only. It does not cover podcasts or videos, and it leaves technical accessibility of digital documents to WCAG and the European standard EN 301 549. For video, the equivalent work is a caption track, and our article on SDH versus closed captions explains which kind your company films need.
It is also worth being clear about what it is not. ISO 24495-1 is a guidance standard: it sets out principles and guidelines, not auditable requirements. There is no official certification of documents against it, and at the time of writing no accredited scheme certifies companies or suppliers to it. A further part with requirements for organisations is being developed within ISO, but until it is published and certification bodies are accredited for it, “ISO 24495-1 certified” is only a supplier’s own statement. The accurate wording is that a document was written or revised following the principles and guidelines of ISO 24495-1.
The family is growing. ISO 24495-2, on legal communication, was published in 2025 and builds on Part 1 for contracts, terms, notices and other legal texts, and further parts are in development.
The four ISO 24495-1 plain language principles
The four ISO 24495-1 plain language principles are best read as a sequence: each one depends on the one before.
Relevant: readers get what they need. Before writing, the writer identifies who the readers are, what they want to do with the document, in what situation they will read it, which document type suits that purpose and what content they need. Everything a reader does not need hides what they do need. For companies this is usually the hardest principle, because documents tend to be written for the issuer (to record a decision, to guard against a claim) rather than for the person who receives them.
Findable: readers can easily find what they need. The structure follows the reader’s questions and tasks, headings tell readers what comes next, information design techniques such as tables, lists and white space help them scan, and supplementary information is kept apart from the main path so it does not interrupt it. In practice, this is the principle that most often turns a document around: moving the decision, the deadline or the action to the top changes more than rewriting every sentence.
Understandable: readers can easily understand what they find. This is the part most people associate with plain language: familiar words, clear sentences, concise paragraphs, an appropriate tone, images where they explain better than words, and a text that holds together so readers can follow how one point leads to the next. Necessary technical terms stay, but they are explained and used consistently.
Usable: readers can easily use the information. The writer evaluates the document while it is being developed, tests it with real readers where possible, and keeps evaluating after publication. A document that has never been tried by its readers has only been assumed to be plain.
The guidelines behind each principle
Under each principle, the standard gives guidelines that explain how to apply it. They are not a rigid checklist of rules and work best when applied with judgement, but they give a team a shared vocabulary and a sequence of work.
The guidelines for usability are the ones companies most often skip: evaluate the document as it develops, evaluate it further with readers, and keep evaluating how readers use it after publication.
This is where the standard differs from most plain language guidelines circulating online. Many in-house writing guides, and much public sector guidance, are lists of word and sentence rules. ISO 24495-1 spends most of its effort on readers, structure and evaluation, and treats word choice as one part of a larger design job. Companies that already have a writing guide do not need to discard it; they can map it against the four principles and see where it is thin, which is usually relevance and evaluation.
Why companies are adopting the standard
No EU law requires companies to comply with ISO 24495-1. What the standard does is give a concrete method for obligations that are already written into law in general terms. The GDPR requires information to data subjects to be concise, transparent, intelligible and easily accessible, using clear and plain language. The Unfair Contract Terms Directive requires written consumer contract terms to be drafted in plain, intelligible language, and where there is doubt about meaning, the interpretation most favourable to the consumer prevails. The Medical Device Regulation requires instructions to be written in terms readily understood by the intended user. And the European Accessibility Act, for consumer banking services, caps the complexity of information at level B2 of the Common European Framework of Reference for Languages; our guide to whether the European Accessibility Act applies to your documents covers its scope.
None of these texts says how to prove that you have met them. A documented method based on an international standard is a far better position than “our lawyers thought it was clear”. For procurement, the standard has a second use: it gives you an objective specification to put in a request for quotation, so suppliers are compared against the same principles instead of their own definitions of clarity.
There is also a business case: letters that are not understood generate calls, procedures that are not followed generate errors, and every unclear source sentence becomes several unclear sentences once translated.
How to apply ISO 24495-1 to company documents
The principles are the same for every document, but the pressure points differ. Five document types cover most of what companies ask about.
Manuals and instructions. Technical documentation already has strong conventions for structure, so the gains are usually in relevance and understandability. Separate what the operator must do from what the engineer wants to explain; put warnings where the action happens, not in a chapter at the front; write one action per step; and use the same term for the same component everywhere, including on the machine’s display. Our guide to user manual translation explains the EU rules on instructions, which assume that users can understand them in their own language.
Contracts and terms. Legal precision and plain language are not opposites. Defined terms, a logical order of clauses, headings that say what each clause does and active sentences that name who must do what make a contract more precise, not less. The work needs a lawyer and a plain language writer together, and the result has to survive translation, which is the subject of our guide to contract translation. ISO 24495-2 adds specific guidance for this kind of legal communication.
Customer letters and notices. These are where the relevance principle pays off fastest. A reader opening a letter about a price change, a claim or a policy renewal wants to know three things: what has happened, what it means for them and what they need to do, by when. Putting those answers in the first paragraph, and the legal background after them, usually removes most follow-up calls.
Policies and procedures. Internal policies are often written to be approved rather than to be used. Applying the findable and usable principles means organising them around the situations employees face, separating the rule from its rationale, and testing them with the people who have to follow them, including staff who read them in a second language.
Multilingual content. For a company that publishes in several languages, the source text is the master for every version. Making it plain once is cheaper than fixing clarity in each language afterwards, and the next section explains why.
Plain language and translation
Plain language and translation are usually handled by different teams, which is a missed opportunity. A plain source text makes translation cheaper, faster and more consistent, and it makes machine translation work better.
The reasons are practical. Ambiguous sentences force translators to guess or send queries, and two translators may resolve the same ambiguity differently. Long sentences with nested conditions are where errors cluster, because their logic must be rebuilt in a different word order. Inconsistent terminology in the source becomes inconsistent terminology in every target language, multiplied. Repetitive, consistently phrased text produces more matches in a translation memory you own, so updates cost less over time.
Machine translation engines, whether dedicated translation engines or general AI models, are also sensitive to source quality. Clear, complete sentences with explicit subjects and consistent terms produce noticeably better raw output, which means less post-editing. A source written in plain language is one of the cheapest ways to improve machine translation post-editing results.
Two cautions apply. First, plainness does not transfer automatically. A literal translation of a plain English text can be stiff or unclear in Italian, German or Spanish, because each language has its own conventions for sentence length, formality and the way instructions are addressed to the reader. The principles have to be applied again in each target language, by linguists who know them. Second, terminology must stay fixed. Plain language never means replacing a defined technical or legal term with a friendlier synonym in one document and not another. A shared technical glossary that keeps terminology consistent across translators and suppliers is what keeps plain language and precision together.
A translation style guide is the natural place to record how the four principles apply in each of your languages: preferred sentence patterns, forms of address, how to write instructions and warnings, and which terms are fixed.
Plain language, Easy-to-Read and accessibility
Plain language is not the same as Easy-to-Read. ISO 24495-1 is written for a broad general audience and aims to improve the main version of a document. Easy-to-Read, known in German as Leichte Sprache, produces a separate, much simpler version for people with cognitive or learning disabilities or very limited reading skills, following its own rules and usually validated by readers from that group. Many organisations need both: a plain main version for everyone and an Easy-to-Read version for the readers who need more support. Deciding which of the two a given document needs is the subject of our comparison of plain language and easy read documents.
Plain language is also not a substitute for technical accessibility. A plain document published as an untagged PDF still fails a screen reader user, which is why the standard refers to WCAG and EN 301 549 for digital accessibility. If your documents must be accessible, the guide on how to make a PDF accessible covers the file side; plain language covers the content.
How to audit a document against ISO 24495-1
Because there is no certification, the useful question is not “does this document comply?” but “does it work for its readers, and can we show how we checked?” A structured review against the four principles answers that, and it can be done on any existing document in a few steps.
Start with the reader and the task. Write down, in one or two sentences, who reads the document, what they need to do or decide, and in what situation. If the team cannot agree on this, the document has no chance of being relevant, and that disagreement is the first finding.
Check relevance. Go through the document and mark every section the reader needs for their task, every section that serves only the issuer, and anything missing that the reader would need. Content that serves the issuer may have to stay, for legal reasons for example, but it can move to an annex or a separate section.
Check findability. Read only the headings and the first sentence of each section. Can a reader predict where to find the answer to their three most likely questions? Is the most important information near the start? Are warnings, deadlines and actions visible without reading everything else?
Check understandability. Look for long sentences with several conditions, passive constructions that hide who must act, undefined abbreviations, inconsistent terms and abstract nouns where a verb would be clearer. Readability formulas can flag problem passages, but they measure surface features only.
Test usability. Give the document to a few people who match the intended readers and ask them to complete realistic tasks: find the deadline, explain what they must do, say what happens if they do nothing. Even a handful of readers reveals problems no internal reviewer will see.
Record and repeat. Write down the reader profile, the findings, what was changed and how it was tested. That record is your evidence that the document was developed following ISO 24495-1, and it makes the next revision faster. For documents that are translated, run the usability check on at least the main target languages as well, not only on the source.
Common pitfalls
The most frequent mistake is to treat plain language as a final edit. A text restructured after legal and technical review has to go through review again, so teams skip it; building the reader profile and structure in at the start costs far less. The second is equating plain with short: removing necessary detail makes a text less usable, and sometimes the plain version is longer because it explains a term or adds an example. The third is applying the principles to the source and then translating literally, so clarity is lost exactly where foreign customers and employees read the text. The fourth is overclaiming, describing a document as certified to a standard that has no certification scheme, which a customer’s legal team can easily challenge.
What to ask a plain language supplier
A few questions separate a structured approach from a copy edit. Ask how the supplier identifies readers and their tasks before rewriting, how they test usability and with whom, how they protect legal and technical terms that must not change, and how the plain version is carried into each target language. And ask how they describe their work in relation to ISO 24495-1: a careful supplier will say they follow its principles and guidelines, not that they certify documents to it.
How DEMA Solutions applies ISO 24495-1
Our plain language service follows the principles of ISO 24495-1:2023 and is used for websites, forms, training material, health information, internal communication and customer information. The work follows the order of the standard: we identify what readers need to know or do, restructure the information around their questions, rewrite the language and explain necessary terms, check whether readers can find the key points and the next action, and, for multilingual projects, recreate the plain result in each target language rather than translating the surface wording.
Because we are also a translation company, plain language and translation can run as one coordinated process. Translation follows an ISO 17100 certified process with a second qualified linguist revising every translation, our in-house DTP team handles layout in the original files, and our teams in Italy, Serbia and Spain work across the languages our clients publish in. Plain language is part of our wider accessibility and inclusive language services, alongside Easy-to-Read versions and accessible PDFs.
Where TUBE fits
For companies that publish plain language content in several languages and update it regularly, TUBE helps keep the agreed wording stable. Your glossary and translation memory control machine translation, every approved translation goes into a memory you own and can export, and leverage reporting shows how much of each update comes from wording you have already approved.
Frequently asked questions
ISO 24495-1:2023, Plain language, Part 1: Governing principles and guidelines, is the international standard for plain language. It defines plain language as communication whose wording, structure and design let intended readers easily find what they need, understand it and use it, and sets out four principles with guidelines for applying them.
Relevant (readers get what they need), findable (readers can easily find what they need), understandable (readers can easily understand what they find) and usable (readers can easily use the information). Each principle comes with guidelines, from identifying readers to testing the document with them.
No. ISO 24495-1 is a guidance standard, and there is currently no official certification of documents against it. A further part with requirements for organisations is being developed within ISO. Until certification exists, the accurate claim is that a document follows the principles and guidelines of ISO 24495-1.
No. It is a voluntary standard. However, several EU laws require clear and plain language, including the GDPR for privacy information and the Unfair Contract Terms Directive for consumer contracts, and the standard is a practical method for meeting those general obligations.
Yes. It is designed for most written languages, although its examples are in English. National adoptions exist, such as DIN ISO 24495-1 in Germany and UNE-ISO 24495-1 in Spain. The principles have to be applied in each language, since a literal translation of plain English is not automatically plain.
Plain language improves the main version of a document for a broad audience. Easy-to-Read creates a separate, much simpler version for people with cognitive or learning disabilities, with its own rules and usually tested by readers from that group.
Usually, yes. Clear, consistent source text reduces queries and errors, produces more reusable matches in translation memory and gives better machine translation output, which reduces post-editing effort.
Make your documents work for their readers
If your contracts, customer letters, manuals or policies need to be clearer, in one language or several, send us a sample and tell us who reads it. We will review it against the four principles of ISO 24495-1 and suggest how to rewrite and translate it.
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