quand + future: the tense English refuses

English says when I arrive, I will call you, with a present for an arrival that has not happened. French puts the future where the event is, in both halves: Quand j'arriverai, je t'appellerai. - When I arrive, I will call you.

Every time conjunction that takes the indicative follows the same rule (avant que and jusqu'à ce que take the subjunctive instead). The trap is si, which looks like a neighbour and never takes a future.

Quand takes a future

Inside a when clause English installs a present and lets the main verb carry the timing. French gives the clause its own tense: if the event is in the future, so is the verb.

• Quand tu arriveras, appelle-moi. - When you arrive, call me.
• Lorsqu'il sera prêt, nous sortirons. - When he is ready, we will go out.
• Je te téléphonerai dès que je rentrerai. - I will phone you as soon as I get home.

The main clause can be a future, an imperative (appelle-moi) or a futur proche: Quand tu arriveras, je vais te montrer quelque chose. - When you arrive, I am going to show you something. Only the quand clause is fixed: in writing, futur simple or futur antérieur.

The time conjunctions

Learn them as a set: each one, with a future event, takes a future verb.

Lorsque is the more formal twin of quand, and aussitôt que of dès que. By the rule, après que takes the indicative, so a future here (many speakers use a subjunctive after it, but exams and careful writing expect the indicative); its opposite avant que takes the subjunctive.

When the present is right: si and habits

Two kinds of clause keep the present, and both look like quand clauses.

Si meaning if never takes a future. Same shape, same verb, two tenses, decided by the conjunction alone:

The si clauses page has the full system. The si that means whether is a different word and does take a future: Je ne sais pas si elle viendra. - I do not know whether she will come.

A habit takes the present after quand, in French as in English:

• Quand il pleut, je reste à la maison. - When it rains, I stay at home. (whenever)
• Quand il pleuvra, je resterai à la maison. - When it rains, I will stay at home. (one coming shower)

If whenever fits the English, the present is right.