In short

Lesson 35 sorted subjunctive from indicative inside that-clauses. This lesson does the same for other conjunctions. Two groups matter. First, a fixed set of connectors - para que, embora, caso, a menos que and friends - always drag a subjunctive behind them, whatever the main verb says: the conjunction alone is the trigger. Second, the time-and-condition words quando, se and logo que, when they point at the future, take a tense English does not have: the future subjunctive (futuro do conjuntivo). Quando chegares, telefono-te - “When you arrive, I’ll call you.” Portuguese marks the still-unreal future event; English just uses the present. Get these two reflexes right and your subordinate clauses stop leaking indicatives.

The rule

Group 1: conjunctions that always take the subjunctive

Some conjunctions carry a built-in note of purpose, concession, or unreal condition, so the verb after them is always subjunctive - you do not weigh the sentence, you react to the word. The core B1 set:

• para que / a fim de que - “so that, in order that” (purpose): Explico devagar para que todos percebam.
• embora / ainda que / mesmo que - “although, even though / even if” (concession): Embora esteja cansado, vou sair.
• caso - “in case, if” (hypothesis): Caso precises de mim, liga.
• a menos que / a não ser que - “unless”: Não vou, a menos que tu venhas também.
• sem que - “without (someone doing)”: Ele saiu sem que ninguém o visse.
• antes que - “before” (something not yet real): Fecha a janela antes que chova.

Use the present subjunctive of Lesson 33 for present or future reference. (When the whole sentence is in the past, these same conjunctions take the imperfect subjunctive - Lesson 46 - but the trigger is identical.)

Group 2: quando, se, logo que and the future subjunctive

The temporal and conditional connectors behave differently. quando (when), se (if), logo que / assim que (as soon as), enquanto (while) and sempre que (whenever) look forward to an event that has not happened yet. Portuguese refuses to call an unrealised future event a fact, so it uses the future subjunctive:

• Quando chegares a casa, telefona-me. - When you get home, call me.
• Se tiveres tempo, ajuda-me. - If you have time, help me.
• Logo que souberes, avisa-me. - As soon as you know, let me know.

Notice the English uses the plain present each time (“arrive, have, know”), which is exactly why learners drop into the Portuguese present indicative here. Resist it: after these words, a future event is future subjunctive.

The flip side: when quando or se points at a habit or general fact, there is no unrealised future, so the indicative returns. Quando chego a casa, janto (“When I get home, I have dinner” - every day) vs Quando chegar a casa, janto (“When I get home, I’ll have dinner” - today).

Building the future subjunctive

One rule handles every verb, regular or irregular:

1. Take the 3rd-person plural of the pretérito perfeito (the eles past form of Lessons 20-21) - e.g. falaram, comeram, tiveram, fizeram.
2. Drop the -am.
3. Add: -, -es, -, -mos, -des, -em.

• falar -> falaram -> falar, falares, falar, falarmos, falardes, falarem.

In a regular verb, what is left after dropping -am is the infinitive itself (falaram -> falar-), and the endings are those of the personal infinitive (Lesson 37), so a regular future subjunctive is spelled the same as the personal infinitive. The two split apart only in irregular verbs, where the past stem shows: ter -> tiver (future subj.) but ter (personal infinitive).

Which tense goes in the main clause

After a future-subjunctive clause the main clause is not subjunctive. It is whatever fits: present indicative with future sense (telefono-te), future (telefonar-te-ei), or an imperative (telefona-me). Only the subordinate verb carries the future subjunctive.

Forms & patterns

Group-1 conjunctions and what each contributes:

Future subjunctive endings (added to the past eles-stem):

Common irregular future subjunctives (from the past stem - eu-form shown):

Examples

Common mistakes

• Quando chegas, telefono-te -> Quando chegares, telefono-te - a future quando takes the future subjunctive, even though English says the plain “arrive”.
• Se tens tempo, ajuda-me (for a future request) -> Se tiveres tempo, ajuda-me - open future se is future subjunctive, not present indicative.
• para que podes entrar -> para que possas entrar - para que is a Group-1 trigger and always takes the subjunctive, never the indicative.
• embora está cansado -> embora esteja cansado - concessive embora governs the subjunctive; the estar indicative está is wrong here.
• Building the future subjunctive from the infinitive: se fazer -> se fizer, se ter -> se tiver - take the past eles-stem (fizeram, tiveram), not the infinitive.
• a menos que vens -> a menos que venhas - a menos que (“unless”) is a fixed subjunctive trigger and takes the present subjunctive, even for a future event - never the future subjunctive of quando and se.
• Quando eu for grande written Quando eu ser grande -> Quando for - ser and ir share the future subjunctive for, not the infinitive ser.

Tips

• Split the connectors into two piles: always-subjunctive (para que, embora, caso, a menos que, sem que, antes que) and future-subjunctive-when-future (quando, se, logo que, enquanto, sempre que). The first pile you obey; the second you check the time.
• To generate any future subjunctive, whisper the eles past form first: “eles fizeram -> se eu fizer.”
• Regular future subjunctive = personal infinitive spelled the same; they diverge only in irregulars (fizer vs fazer). If a verb is regular, you effectively get Lesson 37 for free.
• English hides the future subjunctive behind a present tense (“if you have”, “when you arrive”). Train yourself to feel the future meaning under the English present and switch tenses.
• Do not double up: the main clause after quando/se is present, future, or imperative indicative - never a second subjunctive.
• In Brazil, the future subjunctive is used identically (Quando você chegar, me liga), but the everyday address is você and the pronoun goes before the verb (me liga); European Portuguese prefers tu and telefona-me.