If you have been learning Portuguese long enough, you know that sooner or later you’ve got to come to grips with the Future Subjunctive (Futuro do Conjuntivo).

Why? The answer is simple: we use it all the time.

So, when do we use the Future Subjunctive in Portuguese? In short, we use the Future Subjunctive when referring to possible scenarios in a future time.

Let’s dive in.

Conjugation

Regular verbs

For any  regular verb, you start with the infinitive form and add the following endings (marked in bold):

	Pintar (1st conj.)	Mexer (2nd conj.)	Atrair (3rd conj.)
Eu	pintar	mexer	atrair
Tu	pintares	mexeres	atraires
Você Ele, ela	pintar	mexer	atrair
Nós	pintarmos	mexermos	atrairmos
Vocês Eles, elas,	pintarem	mexerem	atrairem

The verb forms of the Future Subjunctive and the Personal Infinitive are the same for regular verbs. Learn more about the Personal Infinitive: Personal Infinitive: What Is It and When to Use It.

Irregular verbs

The Future Subjunctive endings are the same for irregular verbs. 

However, instead of going from the infinitive form, you start with the  3-person plural of the Preterite tense (Pretérito Perfeito), and replace the -am ending with Future Subjunctive endings:

	Ser foram	Fazer fizeram	Pôr puseram
Eu	for	fizer	puser
Tu	fores	fizeres	puseres
Você Ele, ela	for	fizer	puser
Nós	formos	fizermos	pusermos
Vocês Eles, elas	forem	fizerem	puserem

Usage

Conditional clauses

We use the Future Subjunctive in conditional clauses* introduced by se. 

Note that, in opposition to the Past Subjunctive,  the Future Subjunctive points toward a time ahead and implies realistic expectations (provided that the condition is fulfilled):

Se sair do trabalho mais cedo, vou até à praia. If I finish work earlier, I’ll go to the beach.   Se tiveres tempo, passa pelo supermercado. If you have time, drop by the grocery store.

* Conditional clauses express contingency. In English, conditional clauses are often introduced by if, in case, unless, as long as, among others. 

Time clauses

We use the Future Subjunctive in time clauses* pointing to possible scenarios or situations in the future. 

These time clauses are often introduced by linking words such as quando, enquanto, assim que, logo que, sempre, among others:

Avisa-me assim que chegares. Let me know as soon as you arrive. Não falo contigo enquanto não pedires desculpa I won’t talk to you until you apologize.

* Time clauses locate time as occurring prior, simultaneously, or after that of the main clause (in this case, after). In English, time clauses are often introduced by linking expressions such as before, as soon as, as long as, or until, among others. 

Concessive clauses

We use the Future Subjunctive to exaggerate concession clauses*, as in no matter what.

This usage comprises a repetitive structure – a verb in the present subjunctive is followed by the same verb in the Future Subjunctive:

Diga o que disser, ninguém me ouve. No matter what I say, no one listens to me. Faças o que fizeres, não vai adiantar. Whatever you do, it won’t cut it.

* Concessive clauses express an idea that is in opposition to the main clause. In English, concessive clauses are often introduced with the linking words although, even if, even though, or despite the fact. 

Note that the phrase you see in between verbs – in the examples above, o que –varies depending on the context. Here are a few other possibilities:

Quem	Venha quem vier, será sempre bem recebido. Whoever comes, will always be welcomed. Seja quem for, eu não tenho medo. Whoever it is, I’m not afraid.
Onde	Vá onde for, não se esqueça de levar o guarda-chuva. Wherever you go, don’t forget to bring your umbrella. Vão por onde forem, apanham sempre trânsito. No matter the route they choose, they always catch traffic.
Como	Faça como fizer, o bolo nunca me sai bem. No matter how I do it, the cake never comes out as expected. Venhas como vieres, de carro ou de comboio, o importante é que chegue a horas. Whether you come by car or train, the important thing is that you arrive on time.