My post about using the perfect forms for future tenses briefly explains the idea of using present tenses to express a future meaning. This post specifically addresses using present tenses for time clauses. We often use when, if and other prepositions to express a moment in time in adverb clauses. For example, when the sun goes down means the time of the sunset. For time clauses in the future tense, these adverb phrases should always be formed using the simple present or present perfect tenses. This is important to remember, because time clauses for the future tense do not take future forms – in other words, these time clauses should not include will.
Example of a future tense sentence with a simple present tense time clause
I will phone you when I get home.
This sentence is actually formed of two parts. First, I will phone you – using the future tense. Second, when I get home, using the present tense. When I get home is not in the future tense because it is a time clause. Because it defines a point in time, and not an action to occur in the future, it uses the present tense.
The same is true when we form time clauses with while, before, after, as soon as, until, and till.
- I will study for my school while I am on holiday.
- You are going to do your exercise before you eat dinner.
- Wait by the bus stop until I come back.
Using the present perfect for time clauses
We can use the present perfect tense in the same was for phrases with when, after, until and as soon as. In our example above, we could also use the present perfect, I will phone you when I have got home. The two sentences are very similar, but the present perfect puts more emphasis on the action being completed – when I get home suggests immediately after arriving home, whilst when I have got home suggests the action of returning home is complete, and the phone call may come any time after.
Though in many situations these two can be almost interchangeable, when using the present perfect for time it tells us one action must be completed for the other to happen. In some cases, using the simple present will not make that clear.
- When you have phoned your mother, we’ll eat dinner. – We will eat dinner after the phone call.
- When you phone your mother, we’ll eat dinner. – This makes it sound like we could eat dinner at the time that the phone call is made.
But do not use the perfect tense when two actions occur together:
When I phone your mother, I will ask her about going to dinner. – Not when I have phoned, because it must happen during the phone call.
Often, however, either the simple present or the present perfect will be acceptable.
- I’ll wash up as soon as I finish. or I’ll wash up as soon as I have finished.
Using if for adverb clauses
We use if the same way as when, with simple present or present perfect tenses. However, if expresses a possible time (a conditional clause). Use when for definite times, but if for things that will possibly happen.
- When I go to the shop, I will buy some milk. – You will go to the shop, for sure.
- If I go the shop, I will buy some milk. – It is possible, but not certain, you will go the shop.
- If it stops raining we will go to the park. – You will only go to the park if it stops raining.
- When it stops raining we will go to the park. – You are certain to go to the park, but will wait until the rain is gone.
When and If for Future Time Clauses Exercise
Complete the following sentences using will/won’t for future meanings and present simple or present perfect for time clauses. Answers and explanations can be found below.
- We’re going on holiday, I ________ (tell) you about it when we ________ (come) back.
- We must do something about global warming before ________ (be) too late.
- I don’t want to take the driving test. I ________ (wait) until I ________ (be) ready.
- I ________ (play) tennis tomorrow if the weather ________ (stay) warm.
- When our guest ________ (arrive), tell him to wait for me.
- They ________ (clean) the house after the party ________ (finish).
- Please let me know, when you ________ (find) out.
- ________ (you, miss) me, while I ________ (be) away?
- Joe looks different now. When you next ________ (see) him, you ________ (not, recognise) him.
- I need to get to the bank before they ________ (close).
- I ________ (be) surprised if our team ________ (do not) win.
- When we ________ to Brighton, it ________ (be) very crowded.
- We’re going on holiday, I will tell you about it when we come back. Future for the action, present simple for the adverb clause starting with when. Could use present perfect for have got back.
- We must do something about global warming before it’s too late. Or it is, present simple because before introduces a time clause.
- I don’t want to take the driving test. I will wait until I am ready. Future for the action, present simple for the time clause starting until.
- I will play tennis tomorrow if the weather stays warm. Future tense for the future action, present simple for the conditional adverb clause, using if.
- When our guest arrives, tell him to wait for me. Present simple for the adverb clause using when. Could also be has arrived.
- They will clean the house after the party finishes. Future tense for the action, present simple for the adverb clause following after. Could also be has finished.
- Please let me know, when you find out. Simple tense for the adverb clause, could also use have found for present perfect use.
- Will you miss me, while I am away? Simple present for the adverb phrase using while.
- Joe looks different now. When you next see him, you will not recognise him. Simple present for the adverb phrase using when, future for the action. We cannot use present perfect for the time clause here, because the future action occurs at the same time as the adverb clause.
- I need to get to the bank before they close. Simple present for the adverb clause using before.
- I will be surprised if our team don’t win. Future for the action, present simple for the adverb phrase using if.
- When we go to Brighton, it will be very crowded. Simple for the adverb clause using when, future for the future action.