We use time clauses in English to express that an action or event is based on a certain period of time. Most often, these clauses are introduced by conjunctions such as “before,” “after,” “until,” “while,” “when,” or “whenever.” We can also use phrases such as “the minute,” “the moment,” or “as soon as” to serve the same purpose.

Let’s take a look at all the rules we need to know!

How to Use Time Clauses

When we describe activities that take place in the future, we do not use the future tense (i.e., the modal verb “will”) to introduce the time clause. Rather, the future is simply marked by the main clause.

• John will make dinner when he comes home.
• As soon as the electricity comes back on, I will make tea.
• Don’t start writing until I tell you.
• Whenever you need my textbook, you can take it.
• I will clean my bedroom before my parents get home.
• The crowd fell silent the moment she started singing.
• I will leave for the shops after it stops raining
• Kim will have a bath when she finishes her homework
• We will stop talking as soon as the movie starts

Notice that other future forms also change to use present simple tense in time clauses:

• I am going on holiday. I will be able to relax.
• When I go on holiday, I will be able to relax.
• My sister is talking on the phone. She keeps her door shut.
• My sister keeps her door shut while she talks on the phone.

If we want to describe an activity that takes place at the same time as another future activity, we use the present continuous tense inside the time clause:

• While you are doing your homework, I will watch TV.
• Jane will read while her brother is playing outside.
• While you are sleeping, I will study English grammar.

“When” Can Be Tricky

A common mistake that people make is when the word “when” introduces a noun clause that is the object of a verb. In these cases, “when” needs to be followed by the future tense:

• He doesn’t know when the movie will start.
• I am not certain when the guests will arrive.
• Tara must choose when she will sell her car.

Notice that in the three examples above, we are not dealing with time clauses. This is because “when” is serving a different purpose in these sentences. It is really asking us for information that is tied to the verb. For example, “I don’t know something” or “Tara must choose something.”

Let’s take a moment to review what we’ve learned about time clauses:

We use time clauses to express that an action or event is based on a period of time. These clauses are complete ideas that need subjects, verbs, and objects, but they do not always follow the same verb rules as the main clause, so we need to be extra careful when choosing the appropriate tense to use.

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