Conditional conjunctions (conjunções condicionais) introduce a hypothesis: "if X, then Y." In Portuguese, this small family of words — se, caso, desde que, contanto que, a não ser que, salvo se — is the gateway to one of the most PT-PT features of the whole language: the future subjunctive. English has no analogue for it. Romance learners from Spanish or French are also surprised: their own languages lost the future subjunctive centuries ago. Portuguese kept it, and it is alive and thriving in the most common conditional pattern of the language.
This page first sorts out the four tense patterns that pair with se — these are the backbone and you should come back to them until they are automatic — and then covers the other conditional conjunctions, each of which tends to require a specific subjunctive tense.
Se — the basic conditional
Se means "if" and introduces the most common conditional clause in Portuguese. The big decision with se is which tense to pair it with, and that decision depends on whether the condition is real/likely, hypothetical, counterfactual-present, or counterfactual-past.
The four se patterns — the essential table
| Type | If-clause (se...) | Result clause | Example |
|---|---|---|---|
| Real / likely (present or habitual) | se + presente do indicativo | presente do indicativo / imperativo / futuro | Se tens tempo, ajuda-me. |
| Hypothetical future | se + futuro do conjuntivo | presente do indicativo / imperativo / futuro | Se tiver tempo, ajudo-te. |
| Counterfactual present | se + imperfeito do conjuntivo | condicional (or imperfeito do indicativo) | Se tivesse tempo, ajudava-te. / ajudar-te-ia. |
| Counterfactual past | se + pretérito mais-que-perfeito do conjuntivo | condicional composto (or mais-que-perfeito composto do indicativo) | Se tivesse tido tempo, teria ajudado. |
This four-row table is the single most important grammar reference for conditionals in Portuguese. Memorise the tense pairings — they are not flexible, and mixing them up is the mistake that most loudly marks a learner.
Let us walk through each one.
Pattern 1 — Real / likely condition
This is the simplest pattern: if something is true or habitual, use the present indicative in both clauses. No subjunctive involved.
Se tens tempo, ajuda-me a mudar a mobília.
If you have time, help me move the furniture.
Se chove, a rua enche-se de chapéus.
If it rains, the street fills with umbrellas. (habitual)
This pattern is also used for open-ended general truths: Se estudas, aprendes ("if you study, you learn").
Pattern 2 — Hypothetical future (the PT-PT signature pattern)
This is the pattern that makes Portuguese conditionals distinctive. When the condition refers to a future possibility that has not yet been realised, PT-PT uses the future subjunctive in the se-clause. Spanish does not do this. French does not do this. English does not do this. Portuguese does.
Se tiver tempo amanhã, ajudo-te.
If I have time tomorrow, I'll help you.
Se chover, ficamos em casa.
If it rains, we'll stay home.
Se quiseres, posso passar aí depois do trabalho.
If you want, I can swing by after work.
Se puderes, traz pão.
If you can, bring bread.
The future subjunctive of regular verbs looks deceptively like the infinitive (se chegar, se comer, se partir) — but irregulars have distinctive forms you must learn (se for, se tiver, se puder, se fizer, se souber, se disser, se vier, se quiser).
Pattern 3 — Counterfactual present / unlikely future
When you want to say "if I were X, I would Y" — a hypothesis about the present that is not true, or a future so unlikely you treat it as hypothetical — use the imperfect subjunctive in the se-clause and the conditional (or the imperfect indicative in a more colloquial register) in the result clause.
Se tivesse tempo, ajudava-te.
If I had time, I would help you. (I don't have time right now)
Se ganhasse a lotaria, comprava uma casa à beira-mar.
If I won the lottery, I'd buy a house by the sea.
Se fosse a ti, não dizia nada.
If I were you, I wouldn't say anything.
Two things are distinctively PT-PT here:
- The imperfect indicative in the result clause (ajudava-te) is the everyday choice in speech — the "proper" conditional (ajudar-te-ia) is textbook but reserved for writing and elevated speech. Both are correct.
- The use of mesoclise in the conditional (ajudar-te-ia, dar-lhe-ia) is a PT-PT feature in formal writing. It splits the verb: ajudar
- -te-
- -ia.
- -te-
Pattern 4 — Counterfactual past
When the hypothesis is about a past that did not happen — "if I had done X, Y would have happened" — use the pluperfect subjunctive in the se-clause and the conditional perfect (or the pluperfect indicative compound form) in the result.
Se tivesse tido tempo, teria ajudado.
If I had had time, I would have helped.
Se tivesses avisado a tempo, teríamos mudado os planos.
If you had warned us in time, we would have changed the plans.
Se tivéssemos apanhado o comboio anterior, já estaríamos em casa.
If we had caught the earlier train, we'd already be home.
The pluperfect subjunctive tivesse tido is the form to memorise: tivesse (imperfect subjunctive of ter) + past participle. Its partner in the result clause is teria + past participle. This pattern is the most sophisticated of the four and marks a clear B1/B2 level of control.
Mixing patterns 3 and 4
It is possible — and natural in real speech — to have a counterfactual-past se-clause with a counterfactual-present result, or vice versa:
Se tivesses estudado mais, terias melhor nota agora.
If you had studied more, you'd have a better grade now. (past cause → present result)
Se fosses mais organizado, já terias acabado o projeto.
If you were more organised, you'd already have finished the project. (present trait → past completion)
Caso — "in case that"
Caso is the more formal alternative to se when the condition is introduced as a hypothesis. It always takes the present subjunctive (never the future subjunctive, unlike se). Register: semi-formal to formal; rarer in casual speech.
Caso chova, fica em casa.
In case it rains, stay home.
Caso tenhas alguma dúvida, contacta-me.
Should you have any questions, contact me.
Caso a reunião seja adiada, avisaremos todos por email.
Should the meeting be postponed, we will notify everyone by email.
Desde que — "provided that" (conditional reading)
Desde que has two lives in Portuguese: as a temporal conjunction meaning "since (time)" — desde que saiu, nunca mais ligou ("since he left, he never called again") — and as a conditional conjunction meaning "provided that" or "as long as." The conditional reading is what concerns us here, and it always takes the subjunctive.
Podes ficar, desde que não faças barulho.
You can stay, provided you don't make noise.
Eu assino o contrato, desde que tenhamos garantias por escrito.
I'll sign the contract, as long as we have written guarantees.
Saio contigo hoje, desde que estejas em casa às dez.
I'll go out with you today, as long as you're home by ten.
The tense selected is usually present subjunctive for present/future reference; for future-oriented hypothetical, the future subjunctive is also possible: desde que chegues a horas / desde que chegares a horas. In PT-PT, the present subjunctive is the more common choice.
Contanto que — "as long as"
Contanto que also means "provided that" / "as long as," and always takes the subjunctive. In PT-PT it is less common than desde que — Brazilian Portuguese uses it more freely. A PT-PT speaker will more often reach for desde que or a não ser que.
Contanto que me pagues até ao fim do mês, tudo bem.
As long as you pay me by the end of the month, it's fine.
Farei o jantar, contanto que tu laves a loiça.
I'll make dinner, provided you do the washing up.
You will see this in textbooks more than in real PT-PT prose; treat it as a form to recognise but not necessarily to produce.
A não ser que and a menos que — "unless"
For "unless" clauses, PT-PT has two main options, both taking the subjunctive:
- A não ser que — the natural, everyday PT-PT choice
- A menos que — also acceptable, slightly more bookish in PT-PT
Vou ao parque de manhã, a não ser que chova.
I'm going to the park in the morning, unless it rains.
Não consigo acabar isto hoje, a não ser que me ajudes.
I can't finish this today unless you help me.
A menos que tenhas uma ideia melhor, fazemos como combinado.
Unless you have a better idea, we do as agreed.
Salvo se and exceto se / excepto se — "except if"
Formal alternatives to "unless" are salvo se (literally "save if") and exceto se / excepto se (literally "except if"). All three take the indicative when the condition is real/likely, and the future subjunctive for future-hypothetical reference.
Vamos todos à reunião, salvo se alguém tiver um impedimento.
We're all going to the meeting, unless someone has a conflict.
A consulta é às três, exceto se o médico ligar a remarcar.
The appointment is at three, except if the doctor calls to reschedule.
Summary table of all conditional conjunctions
| Conjunction | Meaning | Mood | Typical tense | Register |
|---|---|---|---|---|
| se (real) | if | indicative | present | neutral |
| se (hypothetical future) | if | subjunctive | future subjunctive | neutral |
| se (counterfactual present) | if | subjunctive | imperfect subjunctive | neutral |
| se (counterfactual past) | if | subjunctive | pluperfect subjunctive | neutral |
| caso | in case, should | subjunctive | present subjunctive | semi-formal |
| desde que (cond.) | as long as | subjunctive | present or future subjunctive | neutral |
| contanto que | provided that | subjunctive | present subjunctive | bookish in PT-PT |
| a não ser que | unless | subjunctive | present subjunctive | neutral (PT-PT preferred) |
| a menos que | unless | subjunctive | present subjunctive | semi-formal |
| salvo se / exceto se | except if, unless | indicative or future subjunctive | varies | formal |
Why does Portuguese keep the future subjunctive?
The future subjunctive survives in Portuguese because the se-clause in pattern 2 ("if I have time tomorrow") genuinely refers to a future hypothetical — an event that has not happened and may not happen. Medieval Iberian Romance marked this with a special tense; Spanish abandoned it (you now say si tengo tiempo), French too (si j'ai le temps), but Portuguese held on. This is one of the features that makes Portuguese subjectively feel more "tense-rich" than its Romance cousins.
Understanding this helps internalise the rule: if you are projecting into an unknown future, Portuguese wants the future subjunctive. If you are describing a habit or a present reality, the indicative is fine.
Common mistakes
❌ Se tenho tempo amanhã, ajudo-te.
Wrong — future reference after *se* takes the future subjunctive, not the present indicative.
✅ Se tiver tempo amanhã, ajudo-te.
If I have time tomorrow, I'll help you.
❌ Se eu seria rico, compraria uma casa.
Wrong — counterfactual *se*-clause needs imperfect subjunctive, not conditional.
✅ Se eu fosse rico, comprava uma casa. / Se eu fosse rico, compraria uma casa.
If I were rich, I'd buy a house.
❌ Caso chove, fica em casa.
Wrong — *caso* always takes the present subjunctive.
✅ Caso chova, fica em casa.
In case it rains, stay home.
❌ A não ser que chegas a horas, não te espero.
Wrong — *a não ser que* takes the subjunctive.
✅ A não ser que chegues a horas, não te espero.
Unless you arrive on time, I won't wait for you.
❌ Se tivesse sabido, tinha vindo.
Acceptable in colloquial speech, but in careful register the result clause should use the conditional compound.
✅ Se tivesse sabido, teria vindo. / Se soubesse, vinha.
If I had known, I would have come.
❌ Se tu quiseres ou não, eu vou.
Awkward — *quer ... quer* is the native construction for this meaning.
✅ Quer queiras, quer não, eu vou. / Queiras ou não, eu vou.
Whether you want (to) or not, I'm going.
Key takeaways
- The four se patterns are the central skill. Real/likely → indicative; hypothetical future → future subjunctive; counterfactual present → imperfect subjunctive + conditional; counterfactual past → pluperfect subjunctive + conditional perfect.
- The future subjunctive after se for future hypotheticals is the most distinctively Portuguese feature of conditionals. Spanish, French, English — none of them do this.
- Caso takes the present subjunctive, not the future subjunctive.
- Desde que and contanto que take the subjunctive and mean "provided that"; in PT-PT, desde que is the natural choice, contanto que is bookish.
- A não ser que is the PT-PT default for "unless"; a menos que, salvo se, exceto se are stylistic variants.
- The conditional in the result clause (ajudaria) is formal; the imperfect indicative (ajudava) is the everyday spoken choice: se tivesse tempo, ajudava-te.
- Mesoclise (ajudar-te-ia, dar-lhe-ia) is a PT-PT formal feature of the conditional — recognise it and be ready to use it in writing.
Related Topics
- Conjunctions OverviewA2 — Words that connect clauses and sentences in Portuguese — from simple *e* and *mas* to the formal *uma vez que* and *dado que*.
- Causal Conjunctions (Porque, Pois, Já que, Visto que)A2 — Expressing cause and reason — from the everyday *porque* to the formal *uma vez que*, *visto que*, and *dado que*, plus the noun-phrase expressions *devido a* and *em virtude de*.
- Concessive Conjunctions (Embora, Ainda que, Mesmo que)B1 — Expressing concession and unexpected outcomes — *embora*, *ainda que*, *mesmo que*, *se bem que*, and the prepositional alternative *apesar de*, all with the subjunctive mood logic explained.