Relative clauses
A relative clause describes a noun using who, which, that, whose, where, or when. Defining relative clauses identify exactly which person or thing you mean and take no commas; non-defining clauses add extra information between commas and never use 'that'. They are a core structure for IELTS Band 7 grammatical range.
The rule
Relative pronouns and when to use them
People (subject)
nounwho/thatverb
The nurse who treated me spoke four languages.
Things
nounwhich/thatclause
The app which tracks my spending saved me a fortune.
Possession
nounwhosenoun
The writer whose novel won the prize lives in Hanoi.
Places
nounwhereclause
The market where we buy vegetables opens at five.
Times
nounwhenclause
I still remember the day when the results arrived.
Object (pronoun can drop)
noun(that/which/whom)subjectverb
The course I chose includes a work placement.
Inside a sentence
The nursenounwhowho/thattreatedverbmespoke four languages.rest of main clause
The coursenounIsubjectchoseverbincludes a work placement.rest of main clause
- subject
- main verb
- key word
Which one do I need?
Who, which or that? Commas or not?
Every answer at a glance
who, with commas
Extra information about a person goes between commas with who. That is never used after a comma, and who cannot be left out.
My cousin, who works as a pilot, has visited forty countries.
which, with commas
Extra information about a thing goes between commas with which, never that, and which cannot be left out.
The Mekong, which flows through six countries, supports millions of farmers.
whose, with commas
Whose replaces his, her, its or their, for people and things. The clause only adds information, so it sits between commas.
Dr Mensah, whose research focuses on air pollution, gave the opening talk.
where / when, with commas
Where means in or at which; when follows a time. The clause is extra, so use commas, and don't add in or there at the end.
We spent a week in Hoi An, where the old town is lit by lanterns at night.
who or that, no commas
The pronoun is the subject of its clause, so it must stay. No commas: the clause tells us which person.
Candidates who arrive late may not be allowed into the exam room.
No pronoun (or that / who)
The pronoun is the object, since a new subject follows, so in a clause without commas you can leave it out. Don't add him or her as well.
The tutor I met at the open day now teaches my IELTS class.
which or that, no commas
The pronoun is the subject of its clause, so it must stay. No commas: the clause tells us which thing.
The scholarship that covers tuition fees is extremely competitive.
No pronoun (or that / which)
The pronoun is the object, since a new subject follows, so in a clause without commas you can leave it out. Don't repeat the noun with it.
The laptop I bought for university has already broken.
whose, no commas
Whose replaces his, her, its or their and works for things as well as people. No commas: the clause tells us which one.
Countries whose economies depend on tourism suffered most during the pandemic.
where / when, no commas
Where means in or at which after a place, and when follows time nouns such as day or year. Don't add in or there at the end.
I'd like to live in a city where cycling is safe.
How to use relative clauses
What is a defining relative clause?
A defining relative clause tells the reader which person or thing you mean; the information is essential, so the clause takes no commas. Remove it and the sentence changes meaning or stops making sense.
In defining clauses you can use who or that for people, and which or that for things. That is slightly more informal and extremely common in speech.
- The bus that stops outside the library goes to the airport.identifies which bus, no commas
- Students who submit late lose ten per cent.defines which students
- The mechanic, that fixed my car, was brilliant.defining clause takes no commas, and that never follows a comma → The mechanic that fixed my car was brilliant.
What is a non-defining relative clause?
A non-defining relative clause adds extra information about a noun that is already fully identified: a name, your only sister, a unique landmark. The clause sits between commas, and if you delete it the sentence still identifies the same person or thing.
Two hard rules follow: non-defining clauses never use that (only who for people, which for things), and the relative pronoun can never be omitted. In speech, the commas surface as short pauses either side of the clause.
- My grandmother, who turns ninety in June, still tends her garden.extra information between commas
- The Bosphorus, which splits Istanbul in two, is busiest at dawn.
- Salvador, that hosts Brazil's biggest carnival, sits on the coast.non-defining clauses never use that → Salvador, which hosts…
Who, which or that, which one do you need?
Who refers to people, which refers to things and animals, and that can replace either, but only in defining clauses. Whose shows possession and works for both people and things. Where stands in for 'in/at which' after places, and when after time nouns like day, year, and moment.
For organisations and companies, careful writing prefers which or that ('the firm that hired me'), even though everyday speech sometimes drifts to who because a company is made of people.
- The volunteers who organised the cleanup collected forty bags of litter.
- An author whose books sell millions rarely needs a day job.whose = possession
- The start-up which office we visited has just been acquired.which cannot show possession → The start-up whose office we visited…
When can you leave out the relative pronoun?
In a defining clause, if the relative pronoun is the object of its clause (a different subject follows it) you can drop the pronoun entirely: 'the film (that) we watched'. This reduced form is the natural rhythm of fluent English, and examiners hear it as native-like economy.
You can never drop a subject pronoun (the clause would lose its subject), and you can never drop anything from a non-defining clause. Quick test: if the word straight after the pronoun is a verb, the pronoun is the subject and must stay.
- The advice she gave me saved the interview.object pronoun dropped, that/which is optional here
- The neighbour lent me his drill has moved away.a subject pronoun cannot drop → The neighbour who lent me his drill has moved away.
- The hotel we stayed at in Hanoi had no lift.pronoun dropped, preposition stays at the end
Why is 'the city which I live there' wrong?
The relative pronoun does not just introduce the clause; it replaces the noun inside it. In 'the photos which she took', which already is the photos, so adding a second pronoun ('which she took them') repeats the noun twice. That extra word is called a resumptive pronoun, and it is one of the most persistent errors for speakers of Arabic, Farsi, Chinese, and Bengali, whose relative clauses genuinely keep such a pronoun.
The fix is a proofreading habit: every time you write a relative clause, scan it for a second pronoun (it, them, there, him, her) that refers back to the head noun. If you find one, delete it; the clause is already complete without it.
- The neighbourhood where I grew up there has changed completely.there repeats where → The neighbourhood where I grew up has changed completely.
- She showed me the photos which she took them in Lagos.them repeats which → the photos which she took in Lagos
- The scholarship that I applied for arrived just in time.for stays, but no extra it; the clause is complete
Common mistakes with relative clauses
Find what is wrong in each one, then open it to check.
1The film which I saw it last night was overrated.What's wrong? Show the fix
The film which I saw last night was overrated.
Which already stands for the film inside the clause; the resumptive it repeats the noun and must be deleted.
2My uncle, that drives a taxi in São Paulo, knows every shortcut.What's wrong? Show the fix
My uncle, who drives a taxi in São Paulo, knows every shortcut.
Non-defining clauses (between commas) never take that; use who for people and which for things.
3People which commute by train read more books.What's wrong? Show the fix
People who commute by train read more books.
Which refers to things; people need who (or that in a defining clause).
4The village where I was born in has no railway station.What's wrong? Show the fix
The village where I was born has no railway station.
Where already contains the idea of 'in which', so adding in doubles the preposition; use where alone, or 'that I was born in'.
5The manager who he interviewed me phoned back the same day.What's wrong? Show the fix
The manager who interviewed me phoned back the same day.
Who is the subject of interviewed; the resumptive he gives the clause two subjects.
6The equipment which were delivered yesterday is faulty.What's wrong? Show the fix
The equipment which was delivered yesterday is faulty.
The verb inside a relative clause agrees with the head noun; equipment is uncountable and singular, so it takes was.
Practise
Write your own
Write a sentence of your own with relative clauses, about you, your studies or your town.
Relative clauses in IELTS
Speaking
- Part 2 cue cards hand you the structure: 'Describe a person who…', 'a place where…'. Echo and extend it in your first sentence: “I'd like to talk about my aunt, who basically raised me.” A non-defining clause in the opening line signals Band 7 range immediately.
- Use where and when instead of splitting into two flat sentences: “That's the stadium where I watched my first derby” compresses two ideas into one accurate complex structure, exactly the flexibility examiners listen for.
Writing
- In Task 1, relative clauses compress data elegantly: “The 45-54 age group, which spent the most in 2015, cut its spending sharply thereafter.” One sentence carries the comparison a Band 6 answer needs two sentences to make.
- In Task 2, define your key terms with defining clauses (“Subjects that develop practical skills deserve equal status”) and keep comma discipline: the Band 7 phrase 'good control of grammar and punctuation' is tested every time you choose between which-with-comma and that-without.