Punctuation in OET Writing: What Examiners Mark and What They Miss
Punctuation in OET writing affects Language marks and clinical clarity. This guide covers commas, semicolons, colons, and apostrophes in professional OET letters — with before/after examples from common errors.
Punctuation is one of the quieter Language failures in OET writing. Candidates focus on grammar and vocabulary, and punctuation errors accumulate in the background — a missing comma here, an incorrect apostrophe there — until the pattern is consistent enough to affect the Language band. This guide covers the four punctuation marks that matter most in professional OET letters, and the clinical conventions that differ from everyday English.
For the full Language criterion, read the OET writing criteria guide.
How examiners assess punctuation
Punctuation is not assessed separately — it falls under Language, alongside grammar, vocabulary, and spelling. The marking rubric distinguishes between occasional errors and systematic errors. Systematic errors (the same type of mistake appearing several times in one letter) push the Language band down; occasional errors in an otherwise clean letter do not.
This means the priority is consistency, not perfection. One comma splice in a letter of 190 words is an occasional error. Four comma splices is a systematic error.
| Punctuation mark | Risk level in OET | Most common error |
|---|---|---|
| Comma | High | Comma splice (joining two sentences with a comma instead of a full stop) |
| Apostrophe | High | Incorrect possessive (patient’s vs patients’), its/it’s confusion |
| Colon | Low | Overuse in lists — often better to write a sentence instead |
| Semicolon | Low | Used where a full stop is cleaner — examiners often mark this as unnecessary |
| Full stop | Low | Missing at the end of a paragraph when the last sentence is long |
Commas — the highest-risk punctuation mark
The comma splice
A comma splice joins two independent clauses with a comma. It is the most common punctuation error in OET letters and the one most likely to appear multiple times in the same letter.
Comma splice: The patient was reviewed in the emergency department, she was commenced on IV fluids.
Correct: The patient was reviewed in the emergency department. She was commenced on IV fluids.
Also correct: The patient was reviewed in the emergency department and commenced on IV fluids.
After introductory phrases
A comma after an introductory phrase is required in formal English and missed often in OET letters.
Missing comma: Following her recent admission Ms Ali was reviewed by the cardiology team.
Correct: Following her recent admission, Ms Ali was reviewed by the cardiology team.
Apostrophes in clinical context
Possessives
Singular noun: the patient’s blood pressure, Dr Ahmed’s referral
Plural noun ending in -s: the patients’ records, the nurses’ station
Irregular plural: the children’s ward, the women’s health clinic (apostrophe before the s when the plural does not end in s)
Its vs it’s
This error appears in OET letters when describing symptoms or medication effects: “The medication’s side effect and it’s impact on the patient.” Correct: “its impact” — no apostrophe. “It’s” only means “it is”. If you can substitute “it is” and the sentence still makes sense, use the apostrophe.
Clinical punctuation conventions
These differ from standard grammar textbook rules and are what the OET examiner — typically trained in Australian or UK clinical English — expects:
- Abbreviations: no full stops — Mr, Dr, mL, mg, ECG, IV, BD, TDS
- Drug names: lower-case in running text — metformin, not Metformin
- Diagnoses: lower-case unless proper noun — hypertension, type 2 diabetes; but Parkinson’s disease, Crohn’s disease
- Ranges: en-dash without spaces — 120–80 mmHg, not 120-80 or 120 – 80
Proofreading punctuation under time pressure
During your 4-minute proofreading routine, make one pass specifically for apostrophes and one for full stops at clause boundaries. These two cover the highest-risk marks. If time runs out before you reach semicolons and colons, the risk to your Language band is minimal — those are low-frequency errors.
To see exactly which punctuation marks are affecting your Language band, submit a letter to the Grammar Checker or send it for full professional marking with written feedback per criterion.
Frequently asked questions
Common questions on this topic — full answers below.
Does punctuation affect OET writing marks?
When should I use a comma in an OET letter?
Should OET letters use semicolons?
How do apostrophes work in OET letters?
Do abbreviations in OET letters need full stops?
Does capitalisation count as punctuation in OET?
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