OET Writing · Updated 2026
The ten language mistakes that cost OET Writing marks
Most candidates who miss a B in Writing don't have a vocabulary problem. They have a small set of recurring accuracy and register errors that appear in nearly every letter they write. These are the ten that come up most, each with the version that loses marks, the version that doesn't, and the rule underneath.
Two things are worth knowing before the list. First, none of these errors is fatal on its own — grades are lost to repetition, not to a single slip. Second, they cluster: a candidate who mixes up tenses usually also drops articles, because both come from writing at speed without a planned timeline. Fixing the planning habit often fixes several at once.
Simple past where the present perfect belongs
Language · Content
The simple past closes a fact off in the past. The present perfect says it is still true today. In a clinical history that difference is the difference between a resolved problem and a current one.
Loses marks
Mrs Alvarez suffered from hypertension for twelve years.
Better
Mrs Alvarez has suffered from hypertension for twelve years.
Rule: Still true at the time of writing → present perfect. Finished and over → simple past.
Present perfect with a specific past time
Language
The mirror image of the first error. Once you name when something happened, the present perfect is ungrammatical.
Loses marks
He has undergone an appendicectomy in 2019.
Better
He underwent an appendicectomy in 2019.
Rule: A stated date or time — in 2019, last March, three weeks ago — forces the simple past.
No past perfect for the earlier of two past events
Language · Conciseness and Clarity
When two things both happened in the past, the past perfect marks which came first. Without it the reader has to work out the order themselves.
Loses marks
When she attended clinic on 4 May, her symptoms worsened for two weeks.
Better
When she attended clinic on 4 May, her symptoms had been worsening for two weeks.
Rule: Earlier event → past perfect. Later event → simple past.
Missing or wrong articles
Language
The most frequent error in OET letters by a wide margin, and the most damaging because it recurs in almost every sentence.
Loses marks
Patient presented with productive cough and was commenced on antibiotic.
Better
The patient presented with a productive cough and was commenced on an antibiotic.
Rule: Countable and singular → it needs an article. First mention → a/an. Already mentioned or uniquely identified → the.
Subject-verb disagreement across a long subject
Language
When words separate the subject from its verb, it's easy to agree with the nearest noun instead of the real subject.
Loses marks
The results of his most recent blood test shows a raised white cell count.
Better
The results of his most recent blood test show a raised white cell count.
Rule: Find the head noun — results, not test — and agree with that.
Case-note abbreviations left in the letter
Genre and Style · Conciseness and Clarity
The notes are shorthand written for the writer. A letter is prose written for a reader, and the reader may not share your local conventions.
Loses marks
Pt c/o SOB and N&V, 3/7 duration. BP 150/95.
Better
The patient complains of shortness of breath, nausea and vomiting of three days' duration. Her blood pressure was 150/95 mmHg.
Rule: Write out everything except units of measurement.
Wrong register for the recipient
Genre and Style
The same clinical fact needs different language for a consultant and for a patient's daughter. Getting this wrong is the fastest way to lose Genre and Style marks.
Loses marks
To a patient's carer: “He is being investigated for a possible neoplasm and requires urgent histological confirmation.”
Better
To a patient's carer: “We have found a growth that we need to examine more closely, so we have arranged an urgent test to find out what it is.”
Rule: Decide who is reading before you write a single sentence, then keep that register throughout.
Casual phrasing in a professional letter
Genre and Style
Friendliness reads as unprofessional in a clinical letter. There are standard formulae, and assessors expect them.
Loses marks
Thanks a lot for seeing this lady. Please get back to me if anything comes up.
Better
Thank you for seeing Mrs Okafor. Please do not hesitate to contact me should you require any further information.
Rule: Neutral and formal throughout, including the closing line.
Prepositions that don't collocate
Language
Clinical English has fixed pairings. These are learned rather than reasoned, and the wrong one is immediately visible to an assessor.
Loses marks
She was diagnosed of type 2 diabetes and referred for the endocrinology clinic on December.
Better
She was diagnosed with type 2 diabetes and referred to the endocrinology clinic in December.
Rule: Learn them as whole phrases: diagnosed with, referred to, admitted to, treated for, presented with, complains of, in December, on 3 December.
Copying case notes instead of rewriting them
Conciseness and Clarity · Language
Copied fragments aren't evidence of your English, so they can't earn Language marks — and the note-form syntax reads as poor clarity on top of that.
Loses marks
Social: lives alone, no family support, ex-smoker 20/day quit 2015, mobility poor since fall.
Better
Mr Duarte lives alone with no family support. He stopped smoking in 2015, having previously smoked twenty cigarettes a day, and his mobility has been poor since a fall.
Rule: Read the note, look away, then write the sentence.
How to actually fix these
Reading a list of errors doesn't change what you write under time pressure. What changes it is catching yourself making the error, repeatedly, on your own letters.
Pick the two from this list you recognise in your own writing and work on those alone for a week. Write a letter, mark it against those two only, and note how many instances you find. When the count reaches zero twice in a row, move to the next two. Trying to fix all ten at once means fixing none of them.
The difficulty is self-marking: your own letter always looks correct, because you already know what you meant. OETgo's Writing Coach annotates each line, names the error type, and rewrites the sentence — so you can see whether the habit you're working on has actually gone.
Check your letter for these ten
One free correction on every new account. No credit card required.
Create free accountFrequently asked questions
Which grammar mistake costs the most marks in OET Writing?
Tense choice in the clinical history. Mixing present perfect and simple past distorts the timeline, so the error costs you under Language and again under Content, because the reader is left unsure when something actually happened.
Do small article errors really affect my OET Writing grade?
Individually, no. Repeatedly, yes. Articles are the single most frequent error type in OET letters, and a letter with a missing or wrong article in most sentences reads as low accuracy under Language even when the clinical content is excellent.
Is it acceptable to use abbreviations in an OET letter?
Only for units of measurement and abbreviations that are universally read as words in clinical prose. Case-note shorthand — SOB, N&V, 3/7, PR — must be written out. The case notes are shorthand; your letter is prose.
Should I use the passive voice in an OET letter?
Sometimes. Use it when the person acting is irrelevant or unknown — 'blood tests were ordered' is fine. Use the active voice when the actor matters, particularly when you are asking the recipient to do something. Whole letters in the passive read as evasive and hurt Genre and Style.
How do I stop copying from the case notes?
Plan on the question paper without looking at your letter, then write the letter without looking back at the notes for phrasing. If a phrase from the notes appears in your letter unchanged and it is longer than about four words, rewrite it in your own sentence.