Time clauses are used in English to demonstrate a period of time based on an action or event, similar to dependent clauses in conditional sentences.

For example, I will cook dinner when I get home. ‘When I get home’ is a clause demonstrating a point in time, based on an action/event (the time that I get home), in place of a time such as I will cook dinner at 7pm.

Time clauses are grammatical units that require subjects, verbs and objects, but they do not always use the same verb rules as the main clause. This article will tell you all about them!

Identifying a time clause

Time clauses are started with adverbs or adverb phrases that show they represent a time (sometimes also functioning as subordinating conjunctions). These include when, after, until, as soon as, before. A clause that starts with an adverb of time like this is not usually a complete grammatical idea, as they work as subordinating conjunctions:

  • When the sun sets,
  • Before the first lesson begins,
  • After my teacher arrives,

Although they have a subject, verb and object, none of these are complete ideas, as they simply point to a time, similar to a clause that simply says “At 7pm.”

This is because when we form a time clause, the adverb of time joins two ideas, linking the main clause to the time in a dependent way. The two clauses could be separate sentences without the adverb of time. Consider the following two clauses:

  • I will master English. I will complete every exercise in my textbook.

Either of these could become a time clause, and therefore make the main clause dependent on the timing of the other:

  • I will master English after I complete every exercise in my textbook.
  • When I master English, I will complete every exercise in my textbook.

Notice, however, that the time clause is no longer in the future tense. Time clauses must be adjusted for certain grammar rules. So watch out for clauses starting with adverbs of time, then consider the following rules.

Time Clause Rules

Patterns for forming time clauses are similar to those for regular clauses, with the same word order (except with an adverb of time first), though time clauses use some particular tense rules.

Time clauses only use different rules for future tenses; when talking about past or present events, you can generally use regular tenses for time clauses.

  • Before we cook pies, we wash our hands.
  • He came home after he finished work.
  • We had dinner before we watched the movie.

For the future, we use the present tenses to talk about future times:

  • He will finish reading the book after he eats dinner. (Not after he will eat dinner.)
  • They are going to the museum before we arrive. (Not before we are going to arrive.)
  • I might practice my pronunciation until my friend’s lesson has finished. (Not until my friend’s lesson will have finished.)

Do not repeat the future tense in clauses with adverbs of time

As you can see in the examples above, when two clauses are joined by adverbs of time the future form should not be repeated.

  • She will meet me after it stops raining. (Not after it will stop raining.)
  • I’ll turn off my computer when he does. (Not when he will.)

Times clauses and the conditionals

Time clauses, or ‘when’ clauses are often compared to ‘if’ clauses. This is a logical comparison because when discussing the future they are grammatically very similar to the first conditional.

  • We will see them when they get here.
  • We will see them if they get here.

In both cases the main clause is dependent on the second clause. A time clause shows the event will happen at a certain time, while the if clause shows it will happen if something else happens. As both make the main clause dependent on another detail (time or something that is possible), the grammatical construction is the same.

So you can practise your time clause grammar further by developing your understanding of the first conditional.

Noun phrases

Be careful, because the future tense may still be used if the time adverb introduces a noun clause. The difference is if the clause is the object of a verb, and not a time clause.

  • I know when the boat will leave.

This answers the question what (You know what.) rather than when.

Time Clauses Exercise

Combine each of the following pairs of sentences by changing one clause into a time clause, using any of the time adverbs, such as when, after, before, unless, until, as soon as. The first one has been done for you:

  • I will read this book. I will eat dinner.
  • I will read this book after I eat dinner.
  1. He will get wet. He is going swimming.
  2. We are meeting the team. The team is arriving at the station.
  3. I got to work late. I got up late.
  4. The police will catch the criminal. The criminal will make a mistake.
  5. They are going on holiday. They are finishing their exams.

Suggested Answers

  1. He will get wet when he goes swimming.
  2. We will meet the team when they arrive at the station.
  3. I got to work late after I got up late.
  4. The police will catch the criminal when he makes a mistake.
  5. They are going on holiday after they finish their exams.

If you found this article useful, please be aware it is also discussed in the book The English Tenses Practical Grammar Guide, available in eBook from this website and paperback format here. Please ask any questions below!

Want to master English grammar?

This article was adapted from The English Tenses Practical Grammar Guide; if you found this useful, the book gives a deep understanding of grammar in use.

Want to master English?

Want to master English?

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