Open conditional clauses express conditions that may or may not happen — real, possible scenarios in the future or in general situations. In English, you simply use the present tense after "if" ("if it rains, we stay home"). Portuguese refuses to let you do this. It demands a special tense called the future subjunctive (futuro do conjuntivo) — a mood that has almost disappeared from Romance languages but is fully alive and obligatory in Portuguese. This page shows you when, why, and how to use it.
A note on the URL: This page lives at
/si-clauses-openfor legacy reasons — older versions of the system used Spanish-style slugs. In Portuguese, the conjunction is always se, never "si". Every example on this page uses the correct Portuguese se.
The core pattern
Open conditional sentences in Portuguese follow this structure:
Se + future subjunctive, (then) present indicative / future indicative / imperative
The future subjunctive sits in the se-clause. The main clause takes whatever tense expresses the consequence naturally — usually the present indicative for immediate consequences, the future for distant ones, or the imperative for instructions.
Se eu puder, vou contigo.
If I can, I'll go with you.
Se chover amanhã, ficamos em casa.
If it rains tomorrow, we'll stay home.
Se quiseres ajuda, diz-me.
If you want help, tell me.
Notice something important: puder, chover, and quiseres are not the infinitives of poder, chover, querer. They are future subjunctive forms. English speakers are tempted to say se eu posso or se chove — but those are both wrong. After se referring to a future or possible situation, Portuguese requires the future subjunctive.
Why the future subjunctive?
Every conditional in Portuguese communicates one of two things: either the condition is a real possibility (open), or it is counterfactual (unreal). The language marks this distinction in the grammar itself, not just in context. The future subjunctive is the grammatical signal of an open, real, still-undetermined condition. It tells the listener: this might happen, it might not, and I am treating it as a genuine possibility.
Contrast this with the imperfect subjunctive (se eu pudesse, "if I could"), which signals a contrary-to-fact situation — something you are presenting as not the case.
Forming the future subjunctive (quick recap)
For regular verbs, the future subjunctive is identical to the personal infinitive for -ar, -er, and -ir verbs:
| Person | falar | comer | partir |
|---|---|---|---|
| eu | falar | comer | partir |
| tu | falares | comeres | partires |
| ele/ela/você | falar | comer | partir |
| nós | falarmos | comermos | partirmos |
| vós | falardes | comerdes | partirdes |
| eles/elas/vocês | falarem | comerem | partirem |
Irregular verbs have a fully irregular future subjunctive stem that derives from the third-person plural preterite. These are the forms you must memorize:
| Verb | eu/ele form | tu form | nós form | eles form |
|---|---|---|---|---|
| ser/ir | for | fores | formos | forem |
| ter | tiver | tiveres | tivermos | tiverem |
| estar | estiver | estiveres | estivermos | estiverem |
| poder | puder | puderes | pudermos | puderem |
| querer | quiser | quiseres | quisermos | quiserem |
| fazer | fizer | fizeres | fizermos | fizerem |
| dizer | disser | disseres | dissermos | disserem |
| vir | vier | vieres | viermos | vierem |
| ver | vir | vires | virmos | virem |
| saber | souber | souberes | soubermos | souberem |
| haver | houver | houveres | houvermos | houverem |
| trazer | trouxer | trouxeres | trouxermos | trouxerem |
Note that ver (to see) has the future subjunctive vir, vires, virmos — which is orthographically identical to the infinitive of vir (to come). Context always resolves the ambiguity.
The three main-clause patterns
Pattern 1: Se + future subjunctive, present indicative
This is the most common combination. You use it when the consequence is generally true or will happen automatically if the condition is met.
Se tu quiseres, eu ajudo-te.
If you want, I'll help you.
Se ele chegar cedo, jantamos juntos.
If he arrives early, we have dinner together.
Se não houver bilhetes, vamos ao cinema outro dia.
If there are no tickets, we'll go to the cinema another day.
The present indicative in the main clause has a future reading here — Portuguese uses the present for scheduled or planned future events much more freely than English does.
Pattern 2: Se + future subjunctive, future indicative
Used when the consequence is projected further into the future, or when you want to emphasize its futurity explicitly.
Se estudares muito, passarás no exame.
If you study hard, you will pass the exam.
Se o voo atrasar, perderemos a reunião.
If the flight is delayed, we will miss the meeting.
The synthetic future (passarás, perderemos, ficará) is less common in everyday speech — most native speakers prefer the ir + infinitive construction or the simple present with future meaning. Both are fine:
Se estudares muito, vais passar no exame.
If you study hard, you're going to pass the exam.
Pattern 3: Se + future subjunctive, imperative
Used to give conditional instructions or advice — "if X happens, do Y."
Se tiveres dúvidas, pergunta!
If you have questions, ask!
The critical English contrast
English speakers almost always get this wrong at first, because English behaves exactly opposite to Portuguese here.
English: if + present indicative → main clause in future > If you arrive early, we will eat together.
Portuguese: se + future subjunctive → main clause in present/future > Se tu chegares cedo, comemos juntos.
You cannot translate English word-for-word into Portuguese. The English sentence uses the present tense ("arrive") for a future hypothetical event, but Portuguese requires the future subjunctive ("chegares") in this exact context. Mapping arrive → chegas (present indicative) is the most common Portuguese error made by English speakers.
Why this is a distinctive Portuguese feature
The future subjunctive has almost vanished from modern Romance languages. Spanish once had it (si yo pudiere) but abandoned it centuries ago except in legal formulae and proverbs. French and Italian never had it in the same productive sense. Portuguese is the only major Romance language where the future subjunctive is a living, obligatory tense used by every speaker every day.
| Language | Open "if I can, I'll go" |
|---|---|
| Portuguese | Se eu puder, vou. |
| Spanish | Si puedo, voy. (present indicative) |
| French | Si je peux, j'y vais. (present indicative) |
| Italian | Se posso, vengo. (present indicative) |
If you have studied Spanish, you will be tempted to use the present indicative after se. Resist this instinct. Using se eu posso in Portuguese sounds immediately like a foreigner or a Brazilian speaker under heavy Spanish influence (even in Brazil, the future subjunctive remains strongly preferred here, though colloquial BP sometimes reaches for the present).
Temporal and conditional conjunctions that also take the future subjunctive
The future subjunctive is not only for se. It is also required after several time-reference conjunctions when the action is projected into the future:
- quando (when)
- assim que (as soon as)
- logo que (as soon as)
- sempre que (whenever)
- enquanto (while / as long as)
- depois de (que) (after)
- antes de (que) — actually takes present subjunctive, careful!
Quando chegares a casa, liga-me.
When you get home, call me.
Assim que souberes algo, avisa-me.
As soon as you know anything, let me know.
Enquanto tu tiveres esse emprego, não te preocupes com dinheiro.
As long as you have that job, don't worry about money.
Sempre que for possível, vamos lá jantar.
Whenever it's possible, we'll go eat there.
English speakers again find this strange: English uses the present indicative after all of these conjunctions. Portuguese uses the future subjunctive whenever the event is in the future and not yet realized.
The imperative form
In the main clause of a conditional, the imperative is extremely common in European Portuguese. Notice how tu imperative works with the familiar second person:
Se precisares de alguma coisa, diz-me.
If you need anything, tell me.
Se quiseres vir, traz uma garrafa de vinho.
If you want to come, bring a bottle of wine.
Se apanhares chuva, seca o cabelo logo.
If you get caught in the rain, dry your hair right away.
Negation in conditional clauses
Negating the se-clause simply uses não in the usual preverbal position:
Se não chover, vamos à praia.
If it doesn't rain, we'll go to the beach.
Se não te sentires bem, fica em casa.
If you don't feel well, stay home.
Se o Pedro não vier, começamos sem ele.
If Pedro doesn't come, we'll start without him.
Zero/generic conditionals (general truths)
When the condition expresses a general law, habit, or recurring truth — not a specific future event — European Portuguese typically uses the present indicative in both clauses, not the future subjunctive. This matches English "if you heat water, it boils."
Se aqueces água a cem graus, ferve.
If you heat water to one hundred degrees, it boils.
Se não comes, não tens energia.
If you don't eat, you don't have energy.
Notice: the future subjunctive is reserved for specific future possibilities, not timeless laws. For general truths, the present indicative is the expected tense.
Fixed expressions using the future subjunctive
Some expressions have become fossilized with the future subjunctive and are worth memorizing as units:
Seja como for, temos de decidir hoje.
Be that as it may, we have to decide today.
Faça o que fizer, ele nunca está satisfeito.
Whatever he does, he's never satisfied.
Onde quer que estejas, pensa em mim.
Wherever you are, think of me.
Venha o que vier, aguentamos.
Come what may, we'll endure.
These build on patterns like X + relative pronoun + X where the second X is in the future subjunctive — a structure English doesn't have directly.
Common Mistakes
Every one of these errors is made daily by English speakers learning Portuguese. Study them.
❌ Se eu posso, vou contigo.
Wrong — present indicative cannot follow se for a future possibility.
✅ Se eu puder, vou contigo.
If I can, I'll go with you.
❌ Se chove amanhã, ficamos em casa.
Wrong — chove is present indicative, but 'tomorrow' marks future.
✅ Se chover amanhã, ficamos em casa.
If it rains tomorrow, we'll stay home.
❌ Quando tu chegas a casa, liga-me.
Wrong — after quando for future events, use the future subjunctive.
✅ Quando tu chegares a casa, liga-me.
When you get home, call me.
❌ Se eu terei tempo, faço-o.
Wrong — the se-clause takes future subjunctive, not future indicative.
✅ Se eu tiver tempo, faço-o.
If I have time, I'll do it.
❌ Se ele vai à festa, eu também vou.
Ambiguous — present ind. can only work for generic habits, not a specific future party.
✅ Se ele for à festa, eu também vou.
If he goes to the party, I'll go too.
Key Takeaways
- Open conditions use se + future subjunctive in the se-clause.
- The main clause takes the present indicative, the future indicative, or the imperative.
- Never translate English "if + present" word-for-word — Portuguese demands the future subjunctive here.
- The same rule applies to quando, assim que, logo que, enquanto, sempre que when referring to future events.
- Use the present indicative in both clauses only for timeless general truths, not specific future possibilities.
- The future subjunctive is one of the most distinctive features of Portuguese and absolutely non-negotiable in this construction.
Related Topics
- Future Subjunctive OverviewB1 — The futuro do conjuntivo — a living, everyday tense in European Portuguese that marks uncertain future events after temporal, conditional, and relative triggers. Almost extinct in Spanish; thriving in Portuguese.
- Regular Future Subjunctive FormsB1 — How to build the future subjunctive from any regular verb — take the 3pl preterite, drop -am, add the endings. Full paradigms for -ar, -er, and -ir verbs, plus the remarkable homograph relationship with the personal infinitive.
- Irregular Future Subjunctive FormsB1 — The handful of Portuguese verbs whose future subjunctive is built from an irregular preterite stem — ser/ir, ter, estar, poder, querer, saber, fazer, dizer, trazer, vir, ver, pôr, dar, haver — with full paradigms and use in everyday sentences.
- Future Subjunctive with Se (Open Conditionals)B1 — How European Portuguese builds open conditional sentences with se + future subjunctive, the three-way conditional typology (open / hypothetical / counterfactual), and why English speakers consistently get this wrong.
- Future Subjunctive: Portuguese vs SpanishB2 — Why European Portuguese uses the future subjunctive constantly while Spanish has let it die — the single most visible grammatical difference between the two languages after ser/estar, with side-by-side contrasts and a typological explanation.
- Unreal Present Conditions (Se + Imperfect Subjunctive)B1 — Contrary-to-fact present conditions in Portuguese use se + imperfect subjunctive with the conditional — or in colloquial speech, the imperfect indicative.