When can you omit a relative pronoun in English?

When it is the object of a defining relative clause. The barge we hired is the same as the barge that we hired, because we is already the subject of hired. You cannot omit a subject pronoun (the barge that leaked) or a pronoun in a non-defining clause with commas (the barge, which we hired, leaked).

Can you drop who as well as that and which?

Yes, when who is an object: the lock-keeper we met. In careful writing some people keep whom (the lock-keeper whom we met), but everyday English drops the word or uses who. You still cannot drop who when it is the subject: the lock-keeper who waved.

Why is The man lives next door is a pilot wrong as a relative clause?

Because who or that is the subject of lives, and a finite clause needs that subject on the page. The man who lives next door is a pilot is the defining version. You can drop the pronoun only in The man we met lives next door, where we is the subject of met.

Can you omit whose, where, or when?

Whose never drops: the skipper whose charts we used. Where and when are often left out after a noun of place or time: the harbour we put into, the year we moved. After reason, English allows the reason I stayed, the reason that I stayed, or the reason why I stayed.

Is it more formal to keep that?

Slightly, in the sense that keeping that can make a long written sentence easier to parse. In speech, dropping the object pronoun is the default. Both are grammatical. What is not a style choice is dropping a subject pronoun or dropping who or which from a clause with commas.

English grammar · Intermediate

Omitting Relative Pronouns: When You Can Drop Who, Which, and That

Written by Eleanor Whitfield, Lead English Curriculum Editor · Reviewed September 2026

In a defining relative clause, English often drops who, which, or that when the relative pronoun is the object of the clause, not the subject. The barge we hired means the barge that we hired. You cannot drop the pronoun when it is the subject (the barge that leaked, not the barge leaked as a relative clause), and you cannot drop it from a non-defining clause with commas.

The barge we hired leaked at the stern.

that or which is dropped because it is the object of hired

What it is

A relative pronoun has two jobs: it points back at a noun, and it plays a role inside its own clause. When that role is object, the clause already has a subject, so the pronoun is optional in a defining clause. The lock we passed and the lock that we passed mean the same thing. When the role is subject, the clause would have no subject without the pronoun, so it must stay: the lock that jammed, never the lock jammed as a relative clause attached to lock.

The visor I borrowed fogged up. (I is the subject of borrowed; the visor is the object, so that or which can disappear.) The visor that fogged up was mine. (that is the subject of fogged, so it stays.)

How to spot it

Find a noun followed by a clause that still has its own subject (I, we, they, the crew). If who, which, or that could sit between the noun and that subject, you are looking at an object relative, and the pronoun can be left out. If the next word is a verb, the missing word would have been the subject, and you cannot drop it.

the quarry they sealed last winter (they is the subject; that is optional)
the quarry that flooded in March (that is the subject of flooded; it stays)
the jetty we tied up to (object of a stranded preposition; pronoun optional)
the skipper who waved from the cabin (who is the subject of waved; it stays)

Whose never drops, because it is not an object pronoun: the barge whose hull we patched. Where, when, and why can often drop after a noun of place, time, or reason (the year we moved, the reason I stayed), but that is a separate pattern.

Omitting Relative Pronouns Quick Reference

Keep or drop the relative pronoun

Role in the clause	Can you drop it?	Example
Object of the verb	yes, in a defining clause	the barge (that) we hired
Object of a preposition at the end	yes, in a defining clause	the jetty (which) we tied up to
Subject of the clause	no	the barge that leaked (not the barge leaked)
Whose (possession)	no	the skipper whose charts we used
Non-defining clause (with commas)	no	the barge, which we hired in May, leaked
After a preposition in front	no, and whom or which is required	the skipper to whom we spoke

Common Omitting Relative Pronouns Examples in English

The drop is allowed in some patterns and blocked in others. Grouped by that split:

Object Pronouns You Can Drop

The visor I borrowed fogged up.: that or which omitted after visor
Here is the chart we annotated.: object of annotated
The foundry they closed still smokes at dawn.: they is the subject of closed
Is this the millrace you mentioned?: object of mentioned, in a question

Read the clause without the noun: I borrowed (the visor). If the noun is the missing object, omission is fine.

Subject Pronouns You Must Keep

The visor that fogged up was mine.: that is the subject of fogged
A skipper who knows this harbour is rare.: who is the subject of knows
The cistern which overflowed stained the wall.: which is the subject of overflowed
Anyone that works the night winch needs gloves.: that is the subject of works

If you delete the pronoun, two verbs collide or the clause loses its subject: the visor fogged up was mine is not English.

People as Objects

The lock-keeper we met waved us through.: who or that omitted; we is the subject
She's the engineer I told you about.: about stranded; who omitted
The divers they hired checked the hull.: object of hired
Who is the person you called from the jetty?: you is the subject; who in the main clause is different

Everyday English prefers dropping who as an object. Whom we met is grammatical but formal, and you still cannot drop whom after a fronted preposition.

Where Dropping Is Blocked

The barge, which we hired in May, leaked at the stern.: commas: non-defining, which stays
the skipper whose charts we used: whose never drops
the quay to which the barge was tied: preposition in front: which stays
What I borrowed fogged up.: fused relative: what means the thing that, and it stays

Commas are the clearest warning. A clause that adds extra information, set off by commas, always keeps who or which and never takes that.

How Omitting Relative Pronouns Works

One test decides almost every case: is there already a subject inside the relative clause?

Drop Only an Object in a Defining Clause

A defining clause identifies which noun you mean and takes no commas. If the relative pronoun is the object, the clause already has a subject (we, I, they, the crew), so the pronoun is extra. English lets you leave it out. The meaning does not change.

The orchard we bought had no well.

that we bought reduced to we bought

Defining plus object: the pronoun can go.

Keep a Subject Pronoun

If the next word after the noun is a verb, the relative pronoun is the subject of that verb. English needs an expressed subject in a finite clause, so who, which, or that must stay. This is the error that produces the barge leaked at the stern when you meant the barge that leaked.

The orchard that flooded lost its lower rows.

that is the subject of flooded

Noun plus verb: keep that, who, or which.

Prepositions Stay at the End When You Drop

In speech, a relative clause often strands its preposition: the jetty we tied up to. Once the pronoun is gone, the preposition cannot move to the front, because there is nothing to sit after it. The formal pair is the jetty to which we tied up, with which kept.

the winch we hauled the cable with

with stranded; which omitted

Dropped pronoun: preposition at the end.

Never Drop in a Non-Defining Clause

A non-defining clause adds a comment, sits between commas, and uses who or which, never that. The pronoun is required even when it is an object: the barge, which we hired in May, leaked. Dropping it would leave a comma splice or a hanging clause.

The lighthouse, which we reached at dusk, had no keeper.

which stays because of the commas

Commas: keep who or which.

Common Mistakes with Omitting Relative Pronouns

Incorrect: The barge leaked at the stern we hired.

Correct: The barge we hired leaked at the stern.

The relative clause has to sit next to the noun it describes. We hired identifies barge, so it belongs immediately after barge, not after the main verb.

Incorrect: The skipper waved from the cabin we met.

Correct: The skipper we met waved from the cabin.

Same placement error, plus the clause we met needs to modify skipper. With the clause at the end, it wrongly looks as if you met the cabin.

Incorrect: The visor fogged up was mine.

Correct: The visor that fogged up was mine.

That is the subject of fogged. A finite clause needs an expressed subject, so the relative pronoun cannot be dropped.

Incorrect: The barge, we hired in May, leaked.

Correct: The barge, which we hired in May, leaked.

A non-defining clause always keeps who or which. Dropping the pronoun after a comma leaves a clause that is not attached to anything.

Prepositions After a Dropped Pronoun

Stranding is the normal spoken pattern, and it is what makes omission possible with prepositional verbs.

Everyday stranding

Keep the preposition at the end of the clause when the pronoun is gone.

the crew we sailed with: with at the end
the harbour we put into: into stranded
the docket I signed for: for stranded

This is standard English, not a mistake to be tidied away in most writing.

Formal fronting

If you move the preposition to the front, you must keep whom or which. You cannot drop the pronoun, and you cannot use that after a fronted preposition.

the skipper to whom we spoke: to whom, formal, pronoun kept
the quay to which the barge was tied: to which, pronoun kept
the winch with which we hauled the cable: with which, not with that

the skipper to who we spoke and the quay to that the barge was tied are both wrong.

Quick Check: Omitting Relative Pronouns

Keep the relative pronoun or drop it. Rewrite if the clause is in the wrong place.

1. the jetty ___ we tied up to (that / nothing)

Answer: nothing (or that)

object of to; dropping is natural

2. the cistern ___ overflowed (that / nothing)

Answer: that

that is the subject of overflowed

3. The orchard flooded lost its lower rows. (fix)

Answer: The orchard that flooded lost its lower rows.

subject relative: keep that

4. the skipper ___ charts we used (whose / nothing)

Answer: whose

whose never drops

5. The lighthouse, ___ we reached at dusk, had no keeper. (which / nothing)

Answer: which

non-defining: keep which

Omitting Relative Pronouns FAQs

When can you omit a relative pronoun in English?: When it is the object of a defining relative clause. The barge we hired is the same as the barge that we hired, because we is already the subject of hired. You cannot omit a subject pronoun (the barge that leaked) or a pronoun in a non-defining clause with commas (the barge, which we hired, leaked).
Can you drop who as well as that and which?: Yes, when who is an object: the lock-keeper we met. In careful writing some people keep whom (the lock-keeper whom we met), but everyday English drops the word or uses who. You still cannot drop who when it is the subject: the lock-keeper who waved.
Why is The man lives next door is a pilot wrong as a relative clause?: Because who or that is the subject of lives, and a finite clause needs that subject on the page. The man who lives next door is a pilot is the defining version. You can drop the pronoun only in The man we met lives next door, where we is the subject of met.
Can you omit whose, where, or when?: Whose never drops: the skipper whose charts we used. Where and when are often left out after a noun of place or time: the harbour we put into, the year we moved. After reason, English allows the reason I stayed, the reason that I stayed, or the reason why I stayed.
Is it more formal to keep that?: Slightly, in the sense that keeping that can make a long written sentence easier to parse. In speech, dropping the object pronoun is the default. Both are grammatical. What is not a style choice is dropping a subject pronoun or dropping who or which from a clause with commas.