Subjunctive triggers
Summary
The subjunctive appears in a que-clause after expressions of will, necessity, emotion or doubt, and after certain conjunctions; it normally requires two different subjects, and certainty in the affirmative keeps the indicative.
Explanation
The subjunctive is a mood used mainly in subordinate clauses introduced by que, to present an action as wished, required, feared or doubted rather than stated as fact. It is triggered by the main clause. Four big semantic families trigger it: will and volition (vouloir que, désirer que, exiger que, préférer que), necessity (il faut que, il est nécessaire que, il vaut mieux que), emotion (être content/triste/surpris que, avoir peur que, regretter que), and doubt or uncertainty (douter que, il est possible que, il se peut que).
A second source of the subjunctive is a fixed list of conjunctions that take it automatically, regardless of meaning: bien que and quoique (although), pour que and afin que (so that), avant que (before), jusqu'à ce que (until), à condition que (provided that), à moins que (unless), sans que (without) and pourvu que (as long as). After these you use the subjunctive even when the idea seems factual: bien qu'il soit malade, il travaille.
The subjunctive normally needs two different subjects across the two clauses. If the subject is the same on both sides, French avoids the subjunctive and uses an infinitive instead: compare je veux que tu partes (two subjects → subjunctive) with je veux partir (one subject → infinitive). The same shift happens with prepositional conjunctions: pour que tu comprennes but pour comprendre; avant que tu partes but avant de partir.
Verbs of opinion and certainty are the classic boundary. In the affirmative, penser que, croire que, espérer que, être sûr que and il est certain que take the indicative, because they assert something as real: je pense qu'il vient. But when these are negated or turned into questions, the certainty weakens and the subjunctive often appears: je ne pense pas qu'il vienne, penses-tu qu'il vienne ? Espérer que is a notable exception that keeps the indicative even so.
Rule of thumb: locate the trigger in the main clause, check that there are two different subjects (otherwise use an infinitive), and then put the subordinate verb in the subjunctive. Memorise the conjunction list, and remember that affirmative certainty (je sais que, je pense que) stays in the indicative while its negative/interrogative can switch. The most common learner error is keeping the indicative after a clear trigger, as in « il faut que tu fais » instead of il faut que tu fasses.
Examples
Il faut que tu fasses tes devoirs. — You have to do your homework. (il faut que (necessity) triggers the subjunctive fasses.)
Je suis content que tu sois là. — I'm glad (that) you're here. (Emotion + que takes the subjunctive sois.)
Bien qu'il soit fatigué, il continue. — Although he is tired, he keeps going. (The conjunction bien que always takes the subjunctive (soit).)
Je veux partir maintenant. — I want to leave now. (Same subject → infinitive partir, not the subjunctive.)
Je ne pense pas qu'il vienne. — I don't think he's coming. (Negated opinion: penser shifts from indicative to subjunctive vienne.)
Nous attendrons jusqu'à ce qu'elle revienne. — We'll wait until she comes back. (jusqu'à ce que requires the subjunctive revienne.)
Common mistakes
Il faut que tu fais tes devoirs.
Il faut que tu fasses tes devoirs.
After a trigger of necessity, will, emotion or doubt followed by que, the verb in the subordinate clause must be in the subjunctive, not the indicative. Il faut que expresses necessity, so it requires the subjunctive: « il faut que tu fasses », not « tu fais ». Learners default to the familiar present indicative because the subjunctive looks unusual, but the trigger forces the mood. The same applies after vouloir que, exiger que, être content que, avoir peur que, douter que and conjunctions like bien que, pour que, avant que and jusqu'à ce que.
Prerequisites
Related rules
subjunctivemoodsubordinate-clauses