Numbers and Dates in OET Letters: Formatting Conventions Examiners Expect

“Pt seen on 10/11/26, bp 120 over 80, started on 5mg.” Every fact in that sentence could be clinically accurate, and every number in it is formatted in a way that an OET examiner is trained to flag. Numbers and dates look like a minor mechanical detail next to content and structure, but OET letters are read by professionals who rely on dates and dosages being unambiguous — and the conventions examiners expect are specific enough that getting them right is a checkable skill, not a matter of style.

Why do numbers and dates matter for your OET Writing band?

The OET Writing sub-test is marked against six official criteria set by CBLA, the OET’s governing body: Purpose, Content, Conciseness & Clarity, Genre & Style, Organisation & Layout, and Language. Number and date formatting sits inside Language, which assesses the accuracy and consistency of mechanics across the entire letter — the same category that covers spelling, punctuation, and grammar.

Two things make this category of error worth fixing specifically, rather than treating it as cosmetic. First, a wrongly formatted date is not just untidy — it is a genuine Content and Clarity risk, because a referral letter exists to transfer clinically important facts to another professional, and a date the reader parses incorrectly (“10/11/26” read as 10 November by a UK reader and 11 October by a US-trained one) can change the clinical picture the receiving doctor builds. Second, like most mechanical habits, number and date formatting tends to be consistent within a single candidate’s writing: a candidate who writes “5mg” without a space usually does it every time the dose appears, and examiners are trained to read a repeated mechanical slip as reduced control over Language, not a one-off typo.

When do you write numbers as digits vs words in OET letters?

The general-English convention most candidates already half-know is a reasonable starting point: spell out numbers one through nine as words, and use digits for 10 and above.

• three tablets, seven days, nine sessions
• 12 tablets, 28 days, 45 minutes

This rule, however, has fixed exceptions that apply specifically to clinical writing, and these exceptions override the general rule even for numbers below 10:

• Ages are always digits: “a 6-year-old child,” not “a six-year-old child.”
• Dosages and measurements are always digits: “5 mg,” “2 mL,” not “five mg.”
• Times are always digits: “at 9 am,” not “at nine am.”
• Dates are always digits (with the month named — covered below).

The logic behind the split is consistent once you see it: general counted quantities follow the readability convention of general English, while clinically load-bearing numbers — the ones a colleague would act on without double-checking — are written in the form that is fastest and least ambiguous to scan, which is digits every time.

How do you write dates in an OET letter?

Write the day, then the month named in full or abbreviated, then the year: 14 October 2026 or 14 Oct 2026. Both forms are acceptable; what matters is that the month is a word, not a number.

The all-numeral date format — “14/10/26” or “10/14/26” — is the single most consequential date error in OET letters, because day-month order and month-day order are both standard, just in different countries. A candidate from a day-month-year background writing “03/04/26” means 3 April. A reader trained on month-day-year format reads the identical string as 4 March. Neither reader is wrong about their own convention; the string itself is simply ambiguous, and an examiner marking Language has no way to credit a date format that could mean two different days depending on who reads it.

Naming the month removes the ambiguity completely, which is exactly why it is the required convention rather than a stylistic preference. This also applies to date ranges: “admitted on 14 October 2026 and discharged on 21 October 2026,” not “admitted 14/10 and discharged 21/10.”

How do you format times, dosages, and measurements?

Times, dosages, and measurements share one underlying rule: the digit and its unit travel together, with a single space between them, and the unit is never optional or abbreviated inconsistently.

Frequency is the one place candidates often reach for shorthand that works against them: “twice daily” or “every 8 hours” is clearer to a general professional reader than Latin prescribing abbreviations like “b.d.” or “q8h,” which OET-aligned house style treats as register that assumes shared clinical shorthand the examiner is not marking you on. Spell frequency out in words, and keep the dose itself in digits with its unit.

What are the most common numbers-and-dates errors in OET letters?

Three patterns account for most of the marks lost in this category, and all three are mechanical enough to eliminate with a dedicated check rather than general proofreading.

1. Inconsistent spacing around units — “5mg” in one sentence and “5 mg” two lines later. Pick the correct form (digit, space, unit) and apply it everywhere, because an examiner reading the same error repeated across a letter reads it as a pattern, not a slip.
2. All-numeral dates — using “14/10/26” because it is faster to type under exam time pressure, then never going back to expand the month. This is worth the extra two seconds per date, every time.
3. Starting a sentence with a numeral — “28 days after surgery, the wound had healed” should either spell out the number (“Twenty-eight days after surgery…”) or, usually the cleaner fix, restructure the sentence so the number sits later: “The wound had healed 28 days after surgery.” Our grammar tips guide covers this sentence-opening rule alongside the seven other most frequent Language-criterion errors.

Numbers and dates also tend to cluster in the same part of a letter — the opening line establishing when a patient was seen, and the history paragraph listing doses and durations — which means a single careless pass through those two sections usually catches most of the errors in the whole letter. If the underlying case notes themselves are where the numbers originate, our guide to reading OET case notes covers how to extract dates and values accurately before they ever reach the page, and our abbreviations guide covers which unit and drug-name shorthand is safe to keep and which reads as unclear to a general professional reader.

A 60-second numbers-and-dates self-check before you submit

Because these are mechanical, closed-set errors, they are fast to check for in a dedicated final pass rather than folded into a general re-read:

1. Find every date. Confirm the month is spelled out or abbreviated as a word, never left as a pair of numerals.
2. Find every dosage and measurement. Confirm each has a single space before its unit, and that the same unit abbreviation is used consistently throughout.
3. Find every number under 10. Confirm it is spelled as a word unless it is an age, dose, measurement, or time, which stay as digits regardless of size.
4. Check the first word of every sentence. Confirm none of them is a numeral.

Our 10-point pre-submission checklist builds this pass into a broader final review alongside structure, register, and content coverage, so numbers-and-dates accuracy is checked as one step rather than something you have to remember separately under time pressure.

Where self-editing hits its limit

Number and date formatting is genuinely easy to miss on a self-read, because the digits and units look clinically correct at a glance even when the spacing or date order is inconsistent — your eye confirms the value is right and skips past the formatting around it. The free Grammar Checker is a useful first pass for catching some of these mechanically, but a full read against all six criteria — checking numbers and dates alongside content, structure, and register together — is what actually confirms a letter is ready to submit. Our OET writing correction service has reviewed more than 11,000 letters since 2014 against the exact criteria examiners use, catching mechanical slips like inconsistent date formats before they cost you Language marks. If you’re comparing options before booking, our pricing page breaks down turnaround and pack sizes from a single letter up to full exam preparation.