OET Writing: the six criteria assessors use, and the mistakes that cost the most

The OET Writing subtest is a single task. You are given a set of case notes about a patient and asked to write a letter, usually to another healthcare professional, in 45 minutes. The first five minutes are reading time, during which you may not write, and the remaining 40 are for the letter. The target length is 180 to 200 words.

That is the whole task, and it looks simple. The reason it is the subtest that most often holds candidates back is that it is marked against six criteria at once, and a letter that is excellent on four of them and weak on two will not reach Grade B. This guide goes through the six criteria as OET publishes them, and the mistakes that cost the most marks under each one. Check occupationalenglishtest.org for the current criteria and sample letters.

1. Purpose

Purpose asks one question: does the reader know, immediately, why you are writing? The assessor is looking for a clear statement near the top of the letter, usually in the first sentence after the opening, and for the purpose to be developed rather than left as a single line.

The most common mistake is to open with the patient's history and only reveal the request in the final paragraph. The reader of a real referral letter needs the request first and the background after. Purpose is scored on a shorter scale than the other criteria, but a low Purpose score pulls the whole letter down.

2. Content

Content asks whether the letter includes the information the reader needs to act, accurately. The case notes contain more than you need, deliberately. Your job is to select what matters for this reader and this request, and to report it correctly.

The costly mistakes are two: leaving out something the reader has to know, such as a current medication or an allergy, and getting a detail wrong, such as a date, a dose or which side the symptom is on. Accuracy against the notes is checked line by line, so copying a number wrongly is a Content error even if the sentence reads beautifully.

3. Conciseness and Clarity

This criterion rewards leaving things out. The case notes always contain details that are irrelevant to the purpose of the letter: a resolved childhood illness, a social detail that does not bear on the request, a routine observation that was normal. Reproducing them makes the letter longer and harder for the reader to use, and the assessor marks that down.

The usual mistake is to treat the notes as a checklist and include everything, often in note order, so the letter becomes a transcription. Decide what the reader needs, write that, and let the rest go. Staying within 180 to 200 words is not a rule on its own, but a letter well over that length is usually carrying irrelevant material.

4. Genre and Style

Genre and Style asks whether the letter reads like a professional letter to this particular reader. That means a polite, formal register; complete sentences rather than note form; no judgemental language about the patient; a level of technical language that suits the reader; and abbreviations only where the reader would certainly recognise them.

Two mistakes stand out. The first is writing in the telegraphic style of the case notes, with articles and verbs missing, because that is what you were reading a minute ago. The second is misjudging the reader: using clinical shorthand in a letter to a patient or carer, or explaining basic terms to a consultant. Read the task instruction for who the letter is to, and write for that person.

5. Organisation and Layout

This criterion covers the shape of the letter: the conventions of a letter are present, the information is in a logical order, and each paragraph has one job. A clear sequence that works for most referral and discharge letters is: purpose, relevant background, current situation, what you are asking the reader to do, close.

The common mistakes are a single block of text with no paragraphs, information scattered so the reader has to assemble the timeline themselves, and a request that appears in two places with slightly different wording. If the reader could find the one thing they most need by glancing at the paragraph openings, the organisation is doing its job.

6. Language

Language covers grammar, vocabulary, spelling and punctuation, judged by their effect on the reader rather than counted as errors. A letter with a few slips that never obscure the meaning can still score well here. A letter where tense, articles and prepositions are wrong often enough that the reader has to re-read a sentence will not.

The mistakes that cost most are the ones that change meaning: the wrong tense turning a past condition into a current one, a missing negative, a dose written ambiguously. Range matters too, but accuracy with the structures you are confident in beats ambition with ones you are not.

Using the five minutes of reading time

You cannot write during reading time, so use it to decide rather than to memorise. Who is the reader, what do they need to do, which notes are relevant to that, and which are not. Candidates who spend reading time planning the letter in their head usually write a shorter, clearer letter than those who start writing the moment the five minutes end.

Practising in a way that moves the score

Writing more letters helps only if each one is marked against the criteria and you can see which criterion is low. Clodia marks practice letters against the same six criteria, with the exact words of your letter quoted under each point, so you can see whether it is Content, Conciseness or Language that is keeping you below the line and work on that one thing next. The case-note packs cover referral, discharge, transfer, update and advice letters across the professions OET serves, and you can type a letter or photograph a handwritten one.

The criteria and the sample letters on occupationalenglishtest.org remain the authority. If a piece of advice you read anywhere, including here, conflicts with them, follow OET.