Conditional Sentences in OET Writing: If Clauses for Recommendations and Advice

“If the pain persists, contact your GP.” Simple enough — until you need to write five of these in one letter, cover a genuine contingency and a polite request to a colleague in the same paragraph, and keep every tense combination correct under exam pressure. Conditional sentences in OET writing carry almost all of the “what to do if things change” content in advice and discharge letters, and they are graded, quietly but consistently, under the Language criterion — one of the six official criteria OET Writing scripts are marked against.

Why do conditional sentences matter so much in OET advice letters?

Almost every OET advice and discharge letter needs to tell the reader what to do under a condition that hasn’t happened yet: a symptom returning, a side effect appearing, a result coming back abnormal. That instruction is a conditional sentence whether or not the candidate recognises it as one. “If the swelling does not reduce within three days, please return to the clinic” is doing real clinical work — it is the safety-net instruction that makes the letter complete under the Content criterion, since a discharge or advice letter without a clear follow-up contingency is missing required content, not just missing a grammar structure.

The grammar matters because it is graded separately, under Language, from whether the contingency itself was the right one to include. A candidate can choose exactly the right follow-up advice and still lose marks for stating it in a tense combination that doesn’t exist in standard English. That gap — correct clinical judgement, incorrect sentence structure — is exactly what this guide is for.

What’s the difference between first and second conditional in OET writing?

English has several conditional forms, but OET letters realistically need only two, and they do different jobs.

The practical rule: if you’re writing about a patient’s condition changing, you almost always want first conditional. If you’re asking a colleague to do something and want to frame the request gently, second conditional is available — but it is a politeness choice, covered in more depth in our modals and hedging guide, not a statement about how likely the outcome is.

Why do candidates default to the wrong conditional?

Second conditional gets overused in exam writing because it sounds more careful, more hedged — and candidates associate hedged language with professionalism. But applying it to a genuine clinical contingency misstates the situation. “If the pain were to persist, she would need to return” suggests the pain persisting is doubtful or remote, when the letter’s whole purpose is to flag that this is a real possibility the reader must be ready to act on. First conditional says exactly that: a plausible if, a direct then. Reserve second conditional for genuinely polite, hypothetical-feeling requests to a colleague — not for the patient-safety instructions that are the actual point of an advice or discharge letter.

What is the mixed-conditional error, and how do I catch it?

This is the error that costs marks most reliably, because it produces a sentence that doesn’t match any standard English pattern at all.

• ❌ “If the rash will spread, stop the cream.” (present-simple if-clause needs no “will”)
• ✅ “If the rash spreads, stop the cream.”
• ❌ “If she was reviewed sooner, she will recover faster.” (mixes second-conditional if-clause with first-conditional main clause)
• ✅ “If she is reviewed sooner, she will recover faster.” (consistent first conditional)
• ❌ “If you would be able to see her today, I am grateful.” (unnecessary “would” inside the if-clause itself)
• ✅ “If you were able to see her today, I would be grateful.” (would belongs only in the main clause)

The pattern across all three: decide which conditional you’re using before you start the sentence, then keep the if-clause tense and the main-clause form consistent with that single choice. Reading the if-clause and the main clause back separately — does each half, alone, sound like correct English? — catches almost every mixed-conditional error before you submit.

Does comma placement actually matter here?

Yes, and it’s a quick, mechanical check once you know the rule. A comma follows the if-clause only when the if-clause opens the sentence:

• “If the pain worsens, return to the emergency department.” (if-clause first → comma)
• “Return to the emergency department if the pain worsens.” (main clause first → no comma)

Both sentences are equally correct; English allows either order. What isn’t correct is a comma inserted into the second pattern out of habit, or no comma at all in the first. This is a small thing individually, but it sits under Conciseness & Clarity alongside other punctuation habits, and a letter with several contingency sentences repeats the same comma decision multiple times — get the rule wrong once and it’s likely wrong throughout.

Should I write “if” or invert with “should”?

English allows a formal inversion that drops “if” entirely: “should the rash spread” instead of “if the rash spreads.” Both are grammatically correct first-conditional structures; “should” inversion simply reads as more formal, which can be useful if a letter already contains several “if” sentences in a row and you want sentence variety without changing meaning.

• “If the rash spreads, stop the cream immediately.”
• “Should the rash spread, stop the cream immediately.”

The two forms are interchangeable in meaning. The error to avoid is switching between them inconsistently within the same sentence rather than choosing one pattern cleanly — for instance, “should the rash spreads” combines the inverted structure with the wrong verb form, which is neither pattern correctly executed.

How does this connect to the Language criterion?

Language is one of six official criteria set by Cambridge Boxhill Language Assessment (CBLA), the body that owns and administers OET, alongside Purpose, Content, Conciseness & Clarity, Genre & Style, and Organisation & Layout. It rewards accurate grammatical range, and conditional sentences are one of the more complex structures candidates are expected to control, precisely because English conditionals have several distinct forms that look superficially similar. A mixed conditional is the kind of error examiners are trained to notice quickly: it doesn’t change the clinical meaning of the sentence, but it is an unmistakable marker of non-native control, and a letter with several of them repeats that signal across the whole script rather than in one isolated line.

For the wider set of tense and structure patterns examiners check beyond conditionals, our OET grammar guide covers the other errors that most often cost Language marks. For the request-softening use of conditionals specifically — writing to a senior colleague rather than giving symptom advice — see the politeness ladder in our modals and hedging guide, which covers the same territory from the modal-verb side rather than the conditional-clause side. And for how conditional advice fits into a complete advice letter’s structure, our OET advice letter guide walks through the letter type where this grammar appears most often.

A self-check for conditional sentences before you submit

Run this pass once your letter is drafted, specifically on every sentence that contains “if,” “should” (in the inverted sense), or a described contingency:

1. Identify the real purpose of the sentence. Is it a genuine clinical contingency (first conditional) or a polite request to a colleague (second conditional is optional here, first conditional is also fine)? Don’t use second conditional for a symptom contingency just because it sounds softer.
2. Check the if-clause tense alone. Read only the if-clause as its own sentence. “If the pain persists” should sound like correct present-tense English on its own, with no “will” inside it.
3. Check the main clause alone. Read only the main clause. It should contain will, should, must, or an imperative — never a second “if,” and never “would” unless the whole sentence is genuinely second conditional.
4. Check the comma. If-clause first needs a comma before the main clause; main clause first needs no comma.
5. Scan for repetition. If your letter has three or more contingency sentences, vary between “if” and inverted “should” rather than repeating identical structure, but keep each individual sentence internally consistent.

This takes under two minutes once you know what you’re looking for, and it catches a structural error that a basic grammar check often misses, because each half of a mixed conditional can look correct in isolation — the error only shows up when the two halves are read together.

The honest limit of self-editing for conditionals

Conditional sentences are one of the grammar patterns candidates are least likely to catch unaided, because a mixed conditional frequently still “sounds fine” when read quickly — the ear fills in the gap the way it does for a typo. The free Writing Checker is a useful first pass for surface grammar and spelling, but spotting a mixed-conditional pattern reliably, across every contingency sentence in a full letter, under exam time pressure, is exactly the kind of check that benefits from an outside reader. Our OET writing correction service has corrected 11,000+ letters since 2014 and reviews your actual letter against all six official criteria, including the tense-and-structure accuracy that conditional sentences fall under — the part of Language that’s hardest to self-assess precisely because your own sentence already makes sense to you.