In short

In Lesson 33 you learned to build the present subjunctive; now you learn when it is required. The core idea: the subjunctive lives in the subordinate clause after que, and it is triggered by what the main clause does. When the main clause states a fact, you keep the indicative (Sei que ele vem, “I know he is coming”). When the main clause expresses a wish, an emotion, an attempt to influence someone, or wraps the idea in an impersonal judgement, the que clause flips to the subjunctive (Quero que ele venha, “I want him to come”). Two conditions must hold together: there is a que clause, and the two clauses have different subjects. Same subject, and Portuguese uses a plain infinitive instead - a distinction English does not force you to make, so it is the thing to watch.

The rule

Think of four trigger families in the main clause. If the verb or expression before que belongs to one of them, the verb after que is subjunctive.

1. Wish and hope (volition)

Verbs of wanting, hoping, and preferring: querer, desejar, esperar, preferir, gostar (que), and the wish-word oxalá (“I hope / God willing”, which takes the subjunctive with no que).

• Quero que fiques aqui. - I want you to stay here.
• Espero que corra tudo bem. - I hope everything goes well.
• Oxalá faça sol amanhã. - I hope it is sunny tomorrow.

2. Emotion and reaction

Any main clause that reacts emotionally to the que clause: gostar que, adorar que, ter pena que, ter medo que, recear que, alegrar-se de que, surpreender que, ser bom / mau que.

• Tenho pena que não possas vir. - I am sorry you cannot come.
• Alegra-me que estejas melhor. - I am glad you are better.
• Surpreende-me que ele já saiba a verdade. - I am surprised he already knows the truth.

3. Influence: ordering, asking, allowing, forbidding

Verbs that push another subject to act: pedir, dizer (= tell to), mandar, ordenar, exigir, aconselhar, sugerir, permitir, deixar, proibir, impedir, evitar.

• Peço-te que tenhas paciência. - I ask you to be patient.
• O médico aconselha que bebas mais água. - The doctor advises you to drink more water.
• Não permitem que fumemos aqui. - They do not allow us to smoke here.

Note dizer: Digo que ele vem = “I say (report) that he is coming” (indicative, a fact); Digo-lhe que venha = “I tell him to come” (subjunctive, an order).

4. Impersonal expressions of judgement, need and possibility

The frame É + adjective/noun + que… when it delivers a value judgement, necessity, doubt or possibility rather than a plain fact: é importante, é preciso, é necessário, é bom, é melhor, é pena, é possível, é provável, pode ser, convém, basta.

• É importante que chegues a horas. - It is important that you arrive on time.
• É preciso que façamos algo. - We need to do something.
• É possível que ele esteja cansado. - It is possible that he is tired.

The adverb talvez (“maybe”) expresses the same possibility without the frame: placed before the verb, it takes the subjunctive with no que (Talvez ele esteja cansado).

The odd ones out are impersonals of certainty: é verdade que, é evidente que, é óbvio que, é claro que assert a fact and therefore keep the indicative (É óbvio que ele está cansado). That indicative-vs-subjunctive contrast is the whole of Lesson 35.

The different-subject condition (the key filter)

A trigger only forces the subjunctive when the two clauses have different subjects. If the subject is the same, drop que and use the infinitive (personal infinitive when needed, Lesson 37):

• Different subjects -> subjunctive: Quero que (tu) saias. - I want you to leave.
• Same subject -> infinitive: Quero sair. - I want to leave (myself).
• Different subjects -> subjunctive: É melhor que (vocês) esperem. - It is better that you wait.
• Impersonal, no named subject -> infinitive: É melhor esperar. - It is better to wait.

Forms & patterns

The machine has three slots: a trigger, the linker que, and a subjunctive verb.

Same subject cancels the trigger and selects the infinitive:

Examples

Common mistakes

• Quero que tu vens -> Quero que tu venhas - a wish verb forces the subjunctive in the que clause; never the indicative.
• Quero que eu saia -> Quero sair - same subject means no que and a plain infinitive; the subjunctive is only for a different subject.
• Espero que ele é feliz -> Espero que ele seja feliz - esperar (hope) triggers the subjunctive; do not slip back to é.
• É importante que estudar -> É importante estudar (general) or É importante que estudes (specific person) - que must be followed by a conjugated subjunctive, never an infinitive.
• Peço que tu tens paciência -> Peço que tenhas paciência - influence verbs (pedir, mandar, aconselhar) take the subjunctive.
• Talvez ele vem -> Talvez ele venha - talvez (“maybe”) signals possibility and requires the subjunctive when it precedes the verb.
• É óbvio que ele venha -> É óbvio que ele vem - impersonals of certainty (é óbvio, é verdade) keep the indicative; only judgement/doubt impersonals trigger the subjunctive.

Tips

• Learn the trigger, not the verb form. Ask “does the main clause wish, feel, push, or judge?” If yes, the que clause is subjunctive; if it merely reports a fact (sei que, vejo que, é verdade que), it is indicative.
• For the four trigger families the reliable filter is two different subjects + que. Miss either and the subjunctive normally drops out: same subject -> infinitive, no que -> no subjunctive. The standing exceptions are the one-word triggers oxalá and clause-initial talvez, which take the subjunctive with no que at all.
• Espero que is your highest-frequency trigger in real speech (espero que sim, espero que gostes) - drill it until que + subjunctive is automatic.
• Watch dizer and pedir: reporting a fact is indicative (disse que vinha), but telling someone to do something is subjunctive (disse-lhe que viesse).
• Oxalá and clause-initial talvez take the subjunctive without any que - treat them as one-word triggers.
• In Brazil the trigger rules are identical, but colloquial speech often drops the subjunctive after talvez (talvez ele vem); in careful EP the subjunctive is expected - keep it.