OET Writing Common Mistakes
Many OET candidates fail writing not because of poor English, but because of repeated, avoidable mistakes. Based on our analysis of 11,000+ corrected OET letters, the mistakes below account for the majority of marks lost by candidates scoring below Grade B (350/500). These patterns are assessed under the six official OET writing criteria developed by Cambridge Boxhill (the joint venture that runs OET).
Understanding Common Challenges
OET writing differs from general English examinations. Fluent sentences alone do not guarantee success if letters do not meet specific examiner expectations.
These challenges can be addressed once errors are properly identified and understood.
The 7 Most Common OET Writing Mistakes
Unclear or Incomplete Purpose
Many letters fail in the first sentence. If the examiner cannot immediately understand why the letter is written, marks are lost under Purpose and Content.
Frequent Issues
Including Irrelevant Case-Note Information
More detail does not mean a higher score. Students often list case notes instead of selecting points that support the specific purpose.
Frequent Issues
Copying Case Notes (No Paraphrasing)
A major issue for many candidates. Examiners expect professional, paraphrased sentences, not word-for-word copying from the notes.
Frequent Issues
Poor Paragraph Organisation
Many letters contain correct information but in the wrong order. This affects Organisation and Layout scores significantly.
Frequent Issues
Grammar That Reduces Clarity
Grammar mistakes do not only lose marks under Language. They also affect clarity and meaning.
Frequent Issues
Informal or Inappropriate Tone
OET writing is professional — not conversational and not academic. Tone errors directly affect your Genre and Style score.
Frequent Issues
Weak Closing and Requests
Some letters end without a clear action. This weakens the impact of your Purpose and Content.
Frequent Issues
Why These Mistakes Keep Repeating
Most students practice independently and may not recognize which mistakes matter most, or how examiners interpret their writing. Without targeted feedback, similar errors tend to recur.
"Without awareness of an error, correction becomes difficult."
Approaches to Address OET Writing Errors
Structured Practice Tools
Use step-by-step writing tools that identify structural errors based on official assessment criteria.
Access Practice ToolsProfessional Feedback
Receive detailed corrections that identify where marks may be lost and provide specific guidance for improvement.
View Feedback OptionsUnderstanding Performance Challenges
Lower scores typically indicate recurring specific errors rather than general language deficiency. Targeted feedback and structured guidance can support meaningful improvement. See exactly which slips drop candidates a grade in our breakdown of the mistakes that cost you grade B.
Next Steps
Access professional correction services to identify and address specific areas for improvement.
View Correction ServicesFrequently asked questions
What are the most common OET writing mistakes?+
The frequent ones are unclear Purpose, including irrelevant case-note detail, wrong register for clinical correspondence, weak paragraph organisation, and recurring grammar errors — each mapping to one of the six OET criteria.
Why do strong clinicians still lose marks?+
Clinical knowledge does not equal letter-writing skill. Marks are lost on genre and register — selecting and sequencing information for a specific reader — which is assessed independently of medical accuracy.
Which mistake costs the most marks?+
Failing to make the Purpose immediately clear is among the costliest, especially under 2026's stricter marking, because it shapes how the whole letter is read.
How do I stop making the same mistakes?+
Get criterion-based human feedback on real letters. Recurring errors are pattern-based, so targeted correction across a few letters fixes them faster than re-reading rules.
Do these mistakes differ by profession?+
The criteria are identical, but typical errors vary — for example, case-note selection differs between a nursing referral and a pharmacy letter.
Want an expert's eyes on your OET letters? Dr Mariam's OET writing correction service marks every letter against all six OET writing criteria and returns line-by-line corrections within 24–72 hours.
See how it works