Complex Sentences for IELTS Writing: A Band 8 Checklist
Quick answer: For Band 8 in IELTS Writing, complex sentences must be accurate, not complicated. The band descriptors reward a wide range of structures with the majority of sentences free of error. Six structures cover almost everything you need: relative clauses, adverbial clauses, noun clauses, participle clauses, conditionals, and cleft sentences.↗ Share on X
To reach Band 8 in IELTS Writing, your complex sentences have to be accurate, not long. The public band descriptors for Grammatical Range and Accuracy reward a wide range of structures where the majority of sentences contain no errors. A long sentence with two mistakes scores lower than a short one with none.
Grammar is one of four criteria in Writing, so it carries roughly a quarter of your Writing score. This article gives you the six structures that cover almost every sentence an examiner wants to see, plus the errors that quietly hold candidates at Band 6.
What does the examiner actually mean by "complex"?
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IELTS Speaking Test: How It Works and How to Score Higher →A complex sentence is one main clause plus at least one dependent clause. That is the grammatical definition, and it is much less impressive than it sounds.
This is complex:
Although public transport is cheaper, many people still drive.
This is not:
Public transport is cheaper, and many people still drive.
The second one is compound: two equal clauses joined by "and". Compound sentences are fine, but a paper made only of them cannot reach the top bands, because it shows one pattern repeated.
Important: "complex" does not mean "long". A 40-word sentence with three subordinate clauses stacked on top of each other usually loses the reader, and loses you marks in Coherence too.
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The six structures that cover almost everything
| Structure | Signal words | Example |
|---|---|---|
| Relative clause | who, which, that, where, whose | Students who study abroad often become more independent. |
| Adverbial clause | although, because, while, since, whereas, if | Although the policy is expensive, it reduces long-term costs. |
| Noun clause | that, what, whether, how | Critics argue that the scheme benefits only wealthy families. |
| Participle clause | -ing or -ed opening | Faced with rising rents, young workers are moving further out. |
| Conditional | if, unless, provided that | If governments invested more in prevention, hospital costs would fall. |
| Cleft sentence | It is... that / What... is | It is the lack of training, not the lack of funding, that limits progress. |
Learn these six well enough to produce them without thinking. That is far more useful than knowing twenty structures you use hesitantly.
How to use each one in a real IELTS paragraph
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Is IELTS Speaking Prep Worth It? What 4 Weeks Can Change →Here is a Task 2 body paragraph that uses four of them without sounding forced:
Many cities have introduced congestion charges to reduce traffic. Although the policy is unpopular at first, it usually cuts the number of cars entering the centre. Drivers who face a daily charge tend to switch to buses or trains. Faced with lower traffic, city councils can then narrow roads and widen pavements. What makes this approach effective is that it changes behaviour without banning anything.
Four structures, four sentences, no sentence over 25 words. That is the texture of a Band 8 paragraph: varied, but calm.
Six errors that cap candidates at Band 6
These are the ones that appear again and again.
1. Double subordination. Writing "Although the cost is high, but it is worth it." English uses "although" or "but", never both. Same with "Because... so...".
2. The comma splice. Joining two full sentences with only a comma: "Technology is useful, it also creates problems." Use a full stop, a semicolon, or a linking word.
3. The fragment. A dependent clause standing alone: "Because many families cannot afford it." That is half a sentence. Attach it to a main clause.
4. "Which" with no clear noun before it. "Prices rose sharply, which the government did not expect." Acceptable in speech, vague in writing. Better: "Prices rose sharply, a change the government did not expect."
5. Subject-verb agreement lost inside a long subject. "The number of students who apply to foreign universities have risen." The subject is "the number", so it is "has risen".
6. Conditional tense mixing. "If governments would invest more, costs will fall." The second conditional needs a past form in the "if" clause and "would" in the other: "If governments invested more, costs would fall."
How many complex sentences should a paragraph have?
There is no quota, and hunting for one is a trap. A useful working target is a mix: in a five-sentence body paragraph, roughly three complex sentences, one compound, and one short simple sentence.
The short simple sentence does real work. Placed after two long ones, it lands the point:
Free university tuition does not remove the cost of living. Students still pay rent, travel, and food, often in expensive cities where part-time work is scarce. The barrier simply moves.
That is a Band 8 rhythm. Complexity everywhere is as monotonous as simplicity everywhere.
A 20-minute drill you can repeat
Do this three times a week with any Task 2 question.
1. Minutes 1 to 3. Write one plain sentence stating your main idea. No linking words at all.
2. Minutes 4 to 10. Rewrite that same idea five times, once with each of the first five structures in the table. Same meaning, different grammar every time.
3. Minutes 11 to 15. Pick the two versions that sound most natural. Say them out loud. If you stumble, the sentence is too heavy.
4. Minutes 16 to 20. Check the two winners against the six errors above, one error at a time. Circle every subject and its verb and confirm they agree.
Keep the winners in a notebook grouped by structure. Over time you build a personal bank of sentence patterns you can produce under exam pressure, which is the only kind of knowledge that helps on test day.
Turning one weak sentence into a Band 8 one
Here is the process applied to a real weak sentence. Start with what a Band 6 candidate typically writes:
Nowadays many people are using social media and it has a lot of bad effects and also some good effects.
Three problems: a wasted opening word, two clauses joined with "and" twice, and no position stated.
Step 1 — cut the filler. "Nowadays", "In today's modern world", "Since the dawn of time" add nothing and examiners see them in every script. Delete.
Step 2 — state one idea per sentence.
Social media use has grown quickly. It brings both benefits and harms.
Step 3 — add one structure, not three. Use a "while" clause to hold the contrast in a single sentence:
While social media has made it easier to stay in touch, it has also made constant comparison unavoidable.
Step 4 — check accuracy. One subject ("social media"), two verbs ("has made", "has made"), both agreeing. No comma splice. No double subordination.
That final version is 20 words, uses one structure correctly, and states a position. It would sit comfortably in a Band 8 paragraph, and it took four small decisions rather than one clever idea.
Which structures are worth the risk?
Not all complex sentences carry equal risk. Some are easy to get right, some are easy to get wrong.
| Structure | Risk of error | Worth using under pressure? |
|---|---|---|
| Adverbial clause (although, while) | Low | Yes, use freely |
| Relative clause (who, which) | Low to medium | Yes, watch agreement |
| Noun clause (that, whether) | Low | Yes |
| Second conditional | Medium | Yes, if you drill the tense pair |
| Participle clause | Medium | Use two or three per essay |
| Cleft sentence | High | One per essay, at most |
Under exam conditions, favour the low-risk rows. A correct "although" clause earns more than a broken cleft sentence, and nobody gets extra credit for degree of difficulty.
Does this apply to Task 1 as well?
Yes, though the useful structures are narrower. Task 1 describes data, so these three do most of the work:
- Relative clauses for comparison: "The category which grew fastest was online retail."
- Participle clauses for trends: "Rising steadily from 2005, the figure peaked in 2012."
- While / whereas clauses for contrast: "Sales climbed in Europe, whereas they fell sharply in Asia."
Resist the urge to squeeze cleft sentences and conditionals into a data description. They usually sound strange there, and strange costs you more than plain would.
What about Speaking?
The same six structures help, but the standard is different. Examiners expect natural speech, with the hesitations and self-corrections that real speakers produce. A memorised cleft sentence delivered perfectly in Part 1 sounds rehearsed, and that works against you.
In Speaking, aim for relative clauses, "because" and "although" clauses, and second conditionals, which come out naturally when you speculate: "If I had more time, I would probably learn an instrument."
Your next step
Take the last Task 2 essay you wrote. Go through it with a pen and underline every subordinating word you used: although, because, which, that, while, if, whereas.
Count them, and count how many different ones there are. Most candidates stuck around Band 6.5 find the same two or three words repeated ten times, usually "because" and "and".
Then rewrite just one body paragraph, replacing your repeated words with three structures from the table you have not used. One paragraph, rewritten properly, teaches you more than a new essay written the old way.
FAQ
Do longer sentences score higher in IELTS Writing?
No. The band descriptors reward range and accuracy, not length. A sentence that runs to 40 words and contains two grammar errors scores lower than a clear 18-word sentence with none. Length also affects Coherence and Cohesion, because a reader who has to re-read a sentence is a reader you have lost.
How many different complex structures do I need for Band 8?
There is no fixed number in the descriptors. What examiners look for is a variety of structures used flexibly, with most sentences error-free. Six structures used confidently and correctly will demonstrate more range than a dozen attempted shakily.
Can I memorise complex sentences before the exam?
Memorising whole sentences to insert regardless of the question tends to backfire, because they rarely fit the topic and examiners notice. What does work is memorising the patterns, then filling them with your own content on the day. Practise the pattern until producing it feels automatic.