Prepositional Phrases of Condition: B2–C1 English Guide

Prepositional phrases of condition help us explain what must happen before something else can happen. Instead of always using simple if sentences, advanced English learners can use phrases such as in case of, in the event of, subject to, on condition that and in the absence of. These expressions are especially useful in formal writing, reports, proposals, instructions and Cambridge exam tasks at B2 and C1 level.

Conditional language helps us explain what must happen before something else can happen. In basic English, we often use if:

• If it rains, we will stay at home.

In this lesson, you will learn useful prepositional phrases related to condition, such as in case of, in the event of, subject to, on condition that, and in the absence of. These phrases help you express conditions more precisely and make your English sound more advanced and natural.

What are Prepositional Phrases of Condition?

Prepositional phrases related to condition show that one thing depends on another.

They can express ideas such as:

• something will happen if another thing happens
• something is allowed only if a condition is met
• something depends on availability, approval, evidence, payment, or agreement
• something would not happen without another factor

Compare these examples:

We will cancel the event if it rains.

We will cancel the event in the event of heavy rain.

The second sentence sounds more formal and is suitable for notices, reports, instructions, and formal emails.

Common Prepositional Phrases of Condition

in case of	if something happens	In case of emergency, call this number.
in the event of	if something happens; formal	In the event of a strike, flights may be cancelled.
subject to	depending on something	The offer is subject to availability.
on condition that	only if	You may borrow the car on condition that you drive carefully.
on the understanding that	with the agreement that	He accepted the job on the understanding that he could work from home twice a week.
provided that	only if; as long as	You can join the course provided that you register in advance.
providing that	only if; as long as	We can have the picnic outside providing that the weather stays dry.
in the absence of	if something is missing	In the absence of clear evidence, no decision can be made.
without	if something does not exist or happen	Without your help, we would not have finished on time.
but for	if it had not been for	But for her quick thinking, the situation could have been much worse.
barring	unless something prevents it	Barring any delays, we should arrive by six.
failing	if something does not happen	Failing a full refund, we will accept store credit.
conditional on/upon	dependent on	The agreement is conditional on final approval.
dependent on/upon	decided or influenced by	Entry to the course is dependent on passing the placement test.
in default of	if something is not provided or done; very formal/legal	In default of payment, the service may be suspended.

In case of

In case of means if something happens. It is often used in instructions, warnings, notices, and official information.

• In case of fire, use the stairs, not the lift.

Be careful: in case of is followed by a noun phrase, not a full clause.

Correct:

• In case of rain, the event will move indoors.

Not natural:

• In case of it rains, the event will move indoors.

Use if or in case with a full clause:

• If it rains, the event will move indoors.

Take an umbrella in case it rains.

In the event of

In the event of is a more formal way of saying if something happens. It is common in policies, contracts, formal notices, reports, and business English.

• In the event of a power cut, the backup generator will start automatically.

This phrase is excellent for formal writing, but it may sound too heavy in casual conversation.

Casual:

• If there is a delay, we’ll call you.

Formal:

• In the event of a delay, passengers will be informed as soon as possible.

Subject to

Subject to means that something depends on another condition. It is very common in formal, business, academic, and legal English.

• The project will begin next month, subject to final approval.

This is a very useful phrase for B2 First and C1 Advanced writing, especially in reports, proposals, formal emails, and announcements.

On condition that

On condition that means only if. It introduces a clear condition that must be accepted.

• She agreed to lend me the money on condition that I paid it back within a month.

On the understanding that

On the understanding that means with the agreement that. It is formal and often used when people agree to something because a particular condition has been promised.

• This phrase is more formal than on condition that and is often used in business or professional contexts.

Provided that / Providing that

Provided that and providing that mean only if or as long as.

• You can attend the advanced class provided that you have completed the intermediate course.

Although these are not pure prepositional phrases, they are very useful conditional expressions and belong naturally in a lesson about condition.

In the absence of

In the absence of means if something is missing or not available. It is formal and useful in academic, professional, and exam writing.

• This phrase is especially useful in essays and reports because it sounds analytical and precise.

Without

Without can express condition when it means if something does not exist or happen.

• Without regular practice, it is difficult to improve your speaking skills.

You can also use without in hypothetical sentences:

• Without her help, I would have made a serious mistake.

But for

But for is an advanced phrase meaning if it had not been for. It is often used in hypothetical situations.

• But for his advice, I would have made the wrong decision.

This phrase is elegant, but it is more common in formal or literary English than in everyday conversation.

Barring

Barring means unless something unexpected happens. It is useful when you expect something to happen, but you know there may be obstacles.

• Barring any delays, we should arrive by seven.

This is a good advanced alternative to unless something goes wrong.

Failing

Failing means if something does not happen or if one option is not possible.

• We hope to receive a full refund; failing that, we will accept a replacement.

This phrase is useful in formal and semi-formal English, especially when discussing alternative options.

Conditional on / dependent on

Conditional on and dependent on mean that something can only happen if another thing happens first.

• The agreement is conditional on government approval.

These phrases are useful in academic, business, and formal contexts.

Very Formal and Legal Phrases

Some conditional phrases are very formal and are mainly used in legal or official English. Learners should recognise them, but they do not need to use them often.

in default of	if something is not paid, provided, or done	In default of payment, access to the service may be suspended.
on pain of	with the threat of punishment	Employees must not disclose confidential information, on pain of dismissal.

These phrases are not suitable for most everyday conversations. They can sound old-fashioned or overly legal, so use them carefully.

Common Mistakes

1. Using “in case of” with a full sentence

Incorrect:

• In case of it rains, we will stay inside.

Correct:

• In case of rain, we will stay inside.
• If it rains, we will stay inside.

2. Confusing “in case” and “in case of”

In case is followed by a clause:

• Take your umbrella in case it rains.

In case of is followed by a noun:

• In case of rain, the event will be moved indoors.

3. Overusing very formal phrases

This sentence is too formal for everyday English:

• Barring unfavourable meteorological conditions, we shall proceed with the picnic.

A more natural version:

• If the weather is good, we’ll have the picnic.
• Barring bad weather, we’ll have the picnic.

Advanced English is not about using the longest phrase possible. It is about choosing the right phrase for the situation.

Useful Phrases for Cambridge Exams

For B2 First, these phrases are especially useful:

in case of	notices, emails, instructions
provided that	essays, emails, reports
without	essays, stories, articles
on condition that	stories, emails, formal writing
subject to	reports, proposals, formal notices

For C1 Advanced, you can also use:

in the event of	reports, proposals, formal letters
in the absence of	essays, academic-style writing
but for	stories, formal writing
barring	articles, reports, advanced speaking
conditional on	formal and academic writing

Final thoughts

Prepositional phrases related to condition are useful because they allow you to move beyond simple if sentences. Phrases such as in case of, in the event of, subject to, on condition that, and in the absence of can make your English sound more precise, formal, and advanced.

For everyday English, use clear and natural phrases such as in case of, without, and provided that. For formal writing and Cambridge exam tasks, try using subject to, in the event of, in the absence of, and on condition that.

The secret is not to sound complicated. The secret is to sound accurate, natural, and appropriate — which is, after all, the real condition for good English.

Related posts:

First Conditional

Second Conditional

Third Conditional 

Mixed Conditionals 

Alternatives to “IF” in English 

Showing  Reference in English 

Prepositional Phrases for Formal Writing 

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