Future time clauses: when, as soon as, if and until

Find the two clauses

A clause is a group of words with a verb, usually with its own subject. A time clause tells you when the main action happens. A condition clause tells you what must be true for a result to happen.

In both sentences, the second clause refers to the future, but its verb has a present form. Find the job of each clause before choosing the verb. Do not put will into both parts just because both refer to later time.

• When the booking arrives, I'll print the tickets.
• If the booking arrives today, I'll print the tickets tonight.

The main clause is not required to contain will. It can contain another future form, a modal verb such as can or might, or an instruction. You will see those choices below.

Form the present verb

For an ordinary future time or open future condition, the present simple is a starting point. Use the base verb with I, you, we and they; add -s or the required spelling change with he, she and it.

After don't or doesn't, use the base verb: doesn't come, not doesn't comes. With be, use am/is/are and am not/isn't/aren't without do. See The present simple and am, is and are: the verb be in the present for all forms.

• We'll take the smaller room if we don't need the extra seats.
• Please stay here until the receptionist is free.

The no-will rule here is about ordinary future reference in these dependent clauses. It is not a rule that every if-clause in English must contain a present verb. Hypothetical and past conditions have other patterns. See The second conditional: unreal situations now or in the future, The third conditional: unreal past situations and Mixed conditionals: when the time is different in the two parts.

Clause order and commas

You can put the time or condition clause first or second. Changing the order does not change which clause needs the present form.

• After the guide checks our names, we'll enter the gallery.
• We'll enter the gallery after the guide checks our names.

Put a comma after a time or condition clause that comes first. In the basic pattern with the main clause first, do not put a comma before the following time or condition clause.

• If you need another copy, ask at the desk.
• Ask at the desk if you need another copy.

Choose the time word

These words do different jobs. Choosing a present verb does not make their meanings the same.

Until describes the endpoint of something that continues. In I won't open the envelope until you get here, the negative means that opening will not happen before your arrival. It does not describe repeated opening throughout the wait.

• We'll wait outside until the doors open.
• We won't go inside until the doors open.

For until compared with a deadline using by, see by, until and by the time. For while and during, see during, for and while.

When or if?

For a particular future event, when presents it as expected or certain to happen. If leaves it as a possibility or condition. This is the speaker's view, not a guarantee about what will really happen.

• When I speak to the manager, I'll mention the missing key. I expect that conversation to happen.
• If I speak to the manager, I'll mention the missing key. The conversation may or may not happen.

Do not choose when only because the event is in the future. If there is a possibility of rain, If it rains tomorrow, we'll move the tables inside makes the rain a condition, not a promised event.

Unless means if not in this type of condition. Even if says that the result still holds despite the condition.

• We'll travel by bus unless the train service improves. if it does not improve
• We'll keep the appointment even if it rains.

These are condition clauses, not time clauses. They share the ordinary future present-form pattern. Read Zero and first conditionals: real conditions and Unless, as long as, provided and in case: other ways to make conditions for the wider choices.

Present simple, continuous or perfect?

A present form does not always mean the present simple. Choose the form for the meaning you need.

Simple: the event or state

• I'll bring the parcel in when I get back.
• We'll sit outside if it isn't windy tomorrow.

Continuous: an action in progress

Use am/is/are plus an -ing form when the condition or time involves an action in progress. British Council also illustrates a future condition with present continuous, and its teacher explanation allows continuous in a future when-clause.

• We'll use the indoor court if it's raining at six tomorrow.
• I'll keep the children out of the kitchen while you're preparing the meal.

Raining and preparing describe activities in progress at the relevant future time. They are not past events.

Perfect: completion before the next action

Use have/has plus the past participle when you want to focus on the first action being complete before the next one. This is present perfect form with future reference, not a report about something already finished now.

• We'll send the invoice after we have checked the final figures.
• I'll put the tools away when I've repaired the shelf.

The simple can also describe this sequence: after we check the final figures. Do not turn a simple-versus-perfect choice into a false rule that only one is grammatical. The perfect makes completion explicit. See The present perfect: form and uses for its form.

The main clause has choices

Match the main clause to the message you want. The present form in the time or condition clause stays the same.

A modal verb helps express ideas such as possibility, permission or obligation. Do not learn the misleading formula 'main clause always will'. British Council and Test-English give other main-clause choices.

By the time: a later extension

By the time introduces the point by which another situation will already be true or another action will already be complete. The by the time clause uses a present form for this future reference.

• By the time the ferry docks, the cafe will be closed.
• By the time you reach the viewpoint, the mist will have cleared.

In the second example, clearing happens before reaching the viewpoint. Will have cleared is the future perfect in the main clause. Reach is present simple in the time clause. Do not put ordinary future will reach there.

The main clause does not always need the future perfect: will be closed describes a future state. See The future continuous, future perfect and future perfect continuous for future perfect forms.

Why will is sometimes possible

The rule is not 'will can never follow if or when'. Look at the meaning and the kind of clause.

Willingness and refusal after if

Will can mean be willing to, rather than simply mark a future event. British Council explicitly allows this use in if-clauses.

• If Jo will take the morning shift, I can cover the evening. if Jo is willing to take it

Won't can mean refuses to. BBC's archived explanation distinguishes refusal from an ordinary future prediction.

• If he won't discuss the problem, we can't reach an agreement. if he refuses to discuss it

An if-clause with will or would can also make a polite request: If you'll sign the visitor book, I'll give you a badge. These are not reasons to insert will into every ordinary future condition.

A later result after if

Cambridge also allows will when the if-clause refers to a later result of the proposed action.

• I'll move the meeting if that will help everyone attend.

Here, helping people attend is the possible result of moving the meeting. This is not the basic pattern of a condition that happens first.

When in a question

A direct or indirect question about time is not a future time clause telling you when another action happens. Will can occur in these questions.

• When will the replacement arrive? a direct question
• I wonder when the replacement will arrive. an indirect question
• I'll fit the part when the replacement arrives. a future time clause

Notice the indirect question's subject-before-will order. See Embedded questions: do you know where..., I don't know what.... Use this distinction rather than deleting will every time you see when.

What comes next

Review The present simple, The present continuous and The present perfect: form and uses for present forms. Compare Present continuous and present simple for the future for future arrangements and schedules, and Will and shall: forms, predictions, decisions and offers for will meanings. Continue with Zero and first conditionals: real conditions, Unless, as long as, provided and in case: other ways to make conditions and by, until and by the time. Later future forms are on The future continuous, future perfect and future perfect continuous; indirect question order is on Embedded questions: do you know where..., I don't know what....