Subjunctive - After Expressions of Necessity

In English, we say "It is necessary that he goes." In French, we change the verb form entirely. This change happens after a 'trigger' phrase. For necessity, the most common trigger is il faut que. This phrase is like a grammar traffic light. When you see it, the light turns green for the subjunctive. You cannot use the regular present tense here. The subjunctive mood shows that the action is a requirement. It isn't just a statement of fact. It is something that *needs* to occur. You are essentially setting a condition for reality. It sounds fancy, but you use it for simple things too. For example, telling a friend they need to leave. Or telling a waiter you need the bill. It is the mood of 'bossiness' and 'obligation.'

1. 1To use this rule, you need to build the subjunctive. Most verbs follow a very simple three-step recipe.
2. 2Start with the ils/elles form of the present tense.
3. 3Drop the -ent ending to find your stem.
4. 4Add the subjunctive endings: -e, -es, -e, -ions, -iez, -ent.
5. 5Let’s look at the verb partir (to leave). The ils form is partent. Drop the -ent and you get part-. Now, add your endings. Il faut que je parte. Il faut que nous partions. Notice that nous and vous look like the imparfait. This is a helpful trick to remember them! Some verbs are rebels and have irregular stems. Verbs like être, avoir, and faire are the usual suspects. You will need to memorize those separately. Think of them as the 'VIPs' of the subjunctive world.

You use the subjunctive after any phrase expressing necessity. These phrases usually start with il est or il faut. Here are the most common triggers you will encounter:

• Il faut que... (It is necessary that / One must...)
• Il est nécessaire que... (It is necessary that...)
• Il est indispensable que... (It is essential that...)
• Il est impératif que... (It is imperative that...)
• Il est essentiel que... (It is essential that...)

Imagine you are in a job interview. You might say, Il est nécessaire que je sois ponctuel (It is necessary that I am punctual). Or imagine you are asking for directions. You might hear, Il faut que vous preniez cette rue (You must take this street). These phrases always require a change in the verb that follows. They set the stage for the requirement.

This is a very important distinction to make. You only use the subjunctive if there is a que and a subject. If you are speaking generally, you don't need it. For example, Il faut manger (One must eat) uses the infinitive. There is no que and no specific person mentioned. Also, if the subject doesn't change, use the infinitive. Instead of saying Il faut que je parte, you could say Je dois partir. The subjunctive requires two different subjects or a specific trigger phrase. If you use il faut without que, just use the basic verb. It saves you a lot of mental energy! Think of que as the bridge to the subjunctive. No bridge, no subjunctive.

The biggest mistake is using the indicative (normal) tense. People often say Il faut que tu vas instead of Il faut que tu ailles. It sounds very jarring to a French ear. Another common slip-up is forgetting the i in nous and vous. You might say Il faut que nous parlons by mistake. The correct form is Il faut que nous parlions. It is a small sound, but it matters! Also, watch out for irregular verbs. Faire becomes fasse, not faise. If you use the wrong stem, the whole sentence collapses. Don't worry, though; even the best learners trip over these. Just keep practicing those irregular stems.

You might wonder about the difference between il faut que and tu dois. Both express necessity, right? Yes, but they use different grammar. Tu dois is followed by an infinitive: Tu dois partir. Il faut que is followed by the subjunctive: Il faut que tu partes. They mean the exact same thing! The subjunctive version just sounds a bit more formal or emphatic. Another contrast is with phrases of certainty. Il est certain que does NOT take the subjunctive. Why? Because there is no doubt or requirement; it is a fact. Necessity is about what *should* be, not what *is*. This distinction is the heart of the subjunctive mood.