The regular future subjunctive is built from the 3pl preterite — and the same rule applies to irregular verbs. The only twist is that their 3pl preterite stems are themselves irregular, so their future subjunctive stems inherit the irregularity. Once you know a verb's preterite stem, you know its future subjunctive stem automatically; the endings are always the same (-, -es, -, -mos, -em).
This page walks through the fifteen or so irregular future subjunctives you will meet in everyday European Portuguese, grouped by pattern. These forms are high-frequency — you will produce at least a few of them every day once you are speaking Portuguese at any reasonable level. They reward drilling.
The formation rule, one more time
Given any verb, take the 3rd person plural of the preterite (eles / elas / vocês), drop -am, add the endings. This works for every verb in Portuguese, regular or irregular.
| Step | ter (3pl pret. tiveram) |
|---|---|
| Drop -am | tiver- |
| Add endings | tiver / tiveres / tiver / tivermos / tiverem |
So the "irregularity" of the future subjunctive is entirely inherited from the preterite. If you have learned the strong preterite forms (tive, fiz, disse, pude, soube, quis, trouxe, pus, vim, vi), you already know the future subjunctive stems — you just need to attach them to the standard endings.
The big eight — learn these first
Eight verbs cover roughly 85% of irregular future subjunctive sentences in real speech. Drill these paradigms until they are automatic. Everything else is a footnote.
1. ser / ir — for
This is the single most important irregular future subjunctive in the language. The forms of ser (to be) and ir (to go) merged historically in their preterite paradigm, and that identity is preserved in the future subjunctive as well. For is both "if I am / he is / you are" and "if I go / he goes / you go." Context always decides.
| Subject | ser / ir (future subj.) |
|---|---|
| eu | for |
| tu | fores |
| ele / ela / você | for |
| nós | formos |
| eles / elas / vocês | forem |
Se for preciso, eu fico.
If it's necessary, I'll stay. (ser)
Quando fores ao supermercado, traz azeite.
When you go to the supermarket, bring olive oil. (ir)
Quem for ao cinema, que leve pipocas.
Whoever goes to the cinema, bring popcorn.
Seja como for, vou à festa.
However it may be, I'm going to the party. (idiomatic, ser)
Se as coisas forem bem, compramos casa este ano.
If things go well, we'll buy a house this year.
The idiom seja como for / seja quem for / seja onde for ("however it may be / whoever it may be / wherever it may be") stacks present and future subjunctive for emphasis. It is a beloved EP construction.
2. ter — tiver
| Subject | ter (future subj.) |
|---|---|
| eu | tiver |
| tu | tiveres |
| ele / ela / você | tiver |
| nós | tivermos |
| eles / elas / vocês | tiverem |
Se eu tiver tempo, passo por aí logo à noite.
If I have time, I'll drop by tonight.
Quando tiveres dúvidas, pergunta-me.
When you have questions, ask me.
Assim que tivermos os resultados, ligamos-lhe.
As soon as we have the results, we'll call you.
Enquanto tiverem apetite, há mais comida.
As long as you (pl.) have appetite, there's more food.
Tiver is absolutely essential. Ter is auxiliary in compound tenses, so tiver + past participle also forms the future perfect subjunctive (quando tiver acabado, "when I have finished"). That is a topic for its own page, but the root stem is the same.
3. estar — estiver
| Subject | estar (future subj.) |
|---|---|
| eu | estiver |
| tu | estiveres |
| ele / ela / você | estiver |
| nós | estivermos |
| eles / elas / vocês | estiverem |
Enquanto estiver a chover, ficamos cá dentro.
While it's raining, we'll stay inside.
Quando estiveres em Lisboa, janta connosco.
When you're in Lisbon, have dinner with us.
Se os miúdos estiverem cansados, levamo-los para casa.
If the kids are tired, we'll take them home.
4. poder — puder
| Subject | poder (future subj.) |
|---|---|
| eu | puder |
| tu | puderes |
| ele / ela / você | puder |
| nós | pudermos |
| eles / elas / vocês | puderem |
Note the close-vowel stem pud-, inherited from the preterite pude / pôde / puderam.
Se puderes, traz-me um pão fresco.
If you can, bring me a fresh loaf.
Quando pudermos marcar férias, eu digo-te.
When we can schedule holidays, I'll tell you.
Liga assim que puderes.
Call as soon as you can.
5. querer — quiser
| Subject | querer (future subj.) |
|---|---|
| eu | quiser |
| tu | quiseres |
| ele / ela / você | quiser |
| nós | quisermos |
| eles / elas / vocês | quiserem |
Faz como quiseres — a decisão é tua.
Do as you wish — it's your decision.
Quem quiser café, que levante o dedo.
Whoever wants coffee, raise your finger.
Se não quiseres vir, não te preocupes.
If you don't want to come, don't worry about it.
Quando quiserem jantar, é só dizerem.
Whenever you want dinner, just say so.
6. saber — souber
| Subject | saber (future subj.) |
|---|---|
| eu | souber |
| tu | souberes |
| ele / ela / você | souber |
| nós | soubermos |
| eles / elas / vocês | souberem |
Quando eu souber, digo-te.
When I know, I'll tell you.
Assim que soubermos a data do voo, compramos os bilhetes.
As soon as we know the flight date, we'll buy the tickets.
Se souberes a resposta, responde no chat.
If you know the answer, reply in the chat.
7. fazer — fizer
| Subject | fazer (future subj.) |
|---|---|
| eu | fizer |
| tu | fizeres |
| ele / ela / você | fizer |
| nós | fizermos |
| eles / elas / vocês | fizerem |
Faça o que fizer, não o convenço.
Whatever I do, I can't convince him.
Se fizeres o jantar, eu lavo a loiça.
If you make dinner, I'll do the dishes.
Quando fizer sol outra vez, vamos à praia.
When it's sunny again, we'll go to the beach.
Faremos o que for preciso fazer.
We'll do whatever needs to be done. (for from *ser*, fazer from *fazer*)
8. dizer — disser
| Subject | dizer (future subj.) |
|---|---|
| eu | disser |
| tu | disseres |
| ele / ela / você | disser |
| nós | dissermos |
| eles / elas / vocês | disserem |
Faz o que te disser, sem discutir.
Do whatever I tell you, without arguing.
Quando ele disser sim, avisa-me.
When he says yes, let me know.
Se te disserem que não, volta a perguntar.
If they tell you no, ask again.
The rest: seven more high-frequency irregulars
These appear less often than the big eight, but still need to be at your fingertips for fluent Portuguese.
trazer — trouxer
Preterite 3pl: trouxeram → stem trouxer-.
| Subject | trazer (future subj.) |
|---|---|
| eu | trouxer |
| tu | trouxeres |
| ele / ela / você | trouxer |
| nós | trouxermos |
| eles / elas / vocês | trouxerem |
Se trouxeres pão, eu trago o queijo.
If you bring bread, I'll bring the cheese.
Quando trouxermos as compras, arrumamos tudo na despensa.
When we bring the shopping, we'll put everything in the pantry.
The x is pronounced /s/ in EP — trouxer sounds roughly like trôsser.
ver — vir
| Subject | ver (future subj.) |
|---|---|
| eu | vir |
| tu | vires |
| ele / ela / você | vir |
| nós | virmos |
| eles / elas / vocês | virem |
Preterite 3pl of ver (to see) is viram → stem vir-. Yes, the future subjunctive of ver is literally spelled vir — which is also the infinitive of vir ("to come"). This is one of the more famous Portuguese collisions. We come back to it below.
Quando vires o João, dá-lhe cumprimentos meus.
When you see João, give him my regards.
Se virmos algo interessante, gravamos.
If we see something interesting, we'll record it.
vir — vier
| Subject | vir (future subj.) |
|---|---|
| eu | vier |
| tu | vieres |
| ele / ela / você | vier |
| nós | viermos |
| eles / elas / vocês | vierem |
Preterite 3pl of vir (to come) is vieram → stem vier-. This one has a diphthong ie throughout.
Quando vieres a Lisboa, fica cá em casa.
When you come to Lisbon, stay at our place.
Se ele vier antes das oito, chega a tempo do jantar.
If he comes before eight, he'll make it for dinner.
Quando os meus pais vierem visitar-nos, temos de fazer uma receita especial.
When my parents come to visit, we have to make a special recipe.
pôr — puser
Preterite 3pl of pôr (to put) is puseram → stem puser-.
| Subject | pôr (future subj.) |
|---|---|
| eu | puser |
| tu | puseres |
| ele / ela / você | puser |
| nós | pusermos |
| eles / elas / vocês | puserem |
Onde puseres as chaves, deixa-as sempre no mesmo sítio.
Wherever you put the keys, always leave them in the same place.
Quando puser a mesa, chamo-vos para jantar.
When I set the table, I'll call you for dinner.
The same pattern applies to all compounds of pôr: compor → compuser, propor → propuser, supor → supuser, dispor → dispuser.
dar — der
Preterite 3pl: deram → stem der-.
| Subject | dar (future subj.) |
|---|---|
| eu | der |
| tu | deres |
| ele / ela / você | der |
| nós | dermos |
| eles / elas / vocês | derem |
Se o patrão te der folga, vem connosco à praia.
If the boss gives you a day off, come to the beach with us.
Quando der tempo, lê este artigo.
When there's time, read this article.
Se derem cabaças, nem sempre é mau sinal.
If they reject you, it's not always a bad sign. (idiomatic: *dar cabaças* = to be turned down)
haver — houver
Preterite 3pl: houveram → stem houver-. Mostly used in its impersonal 3sg form.
| Subject | haver (future subj.) |
|---|---|
| (impersonal) | houver |
| eles / elas / vocês | houverem |
Se houver problemas, liga-me.
If there are any problems, call me.
Enquanto houver vida, há esperança.
As long as there's life, there's hope.
Quando houver uma decisão, avisamos-vos.
When there's a decision, we'll let you know.
The ver / vir confusion — and how to keep them straight
This is the single most treacherous detail in the irregular future subjunctive. The infinitive vir means "to come." But the future subjunctive of ver ("to see") is also vir. And the future subjunctive of vir (to come) is vier. Written out:
| Verb | Infinitive | Future subj. (eu / ele) |
|---|---|---|
| ver (to see) | ver | vir |
| vir (to come) | vir | vier |
So the word vir can be either (a) the infinitive of vir meaning "to come," or (b) the 1sg/3sg future subjunctive of ver meaning "see." And the form vier is unambiguously the future subjunctive of vir.
Quero vir contigo ao cinema.
I want to come to the cinema with you. (vir = infinitive of vir, to come)
Quando vir a tua irmã, digo-lhe olá.
When I see your sister, I'll say hi. (vir = 1sg future subj. of ver, to see)
Quando vier a tua irmã, dizemos-lhe olá.
When your sister comes, we'll say hi. (vier = 3sg future subj. of vir, to come)
The context — what verb the sentence is about — clears the ambiguity instantly. But when learning, do not be surprised by the overlap. A Portuguese person never confuses them because they track the meaning, not just the form.
The ser / ir identity — for for both
We flagged this at the top, but it deserves reinforcing. The future subjunctive form for serves two different verbs:
- ser (to be): Se for verdade, fico chocada. ("If it's true, I'll be shocked.")
- ir (to go): Quando eu for a Lisboa, vou ao castelo. ("When I go to Lisbon, I'll visit the castle.")
Exactly like the preterite fui / foi / foram serving both verbs. Portuguese has lived with this coincidence for a thousand years and it causes no real confusion — the context always makes the verb clear. A phrase like se for preciso is unmistakably ser (because "necessary" is an attribute), while quando for à praia is unmistakably ir (because ir + a + place).
Seja como for, vou acabar isto hoje.
However it may be, I'm going to finish this today. (ser)
Se eu for ao mercado, compro fruta.
If I go to the market, I'll buy fruit. (ir)
Smaller players to recognise
Some less frequent but still useful irregular future subjunctives:
| Verb | 3pl pret. | Future subj. (eu) | Example |
|---|---|---|---|
| caber (to fit) | couberam | couber | Se couber no carro, levamos. |
| crer (to believe) | creram | crer | Quem crer, que siga em frente. |
| ler (to read) | leram | ler | Quando leres o livro, fala-me dele. |
| rir (to laugh) | riram | rir | Quem rir por último, ri melhor. |
| perder (to lose) | perderam | perder | Se perderes o comboio, liga-me. |
| ouvir (to hear) | ouviram | ouvir | Quando ouvires a sirene, sai. |
Most of these follow the regular recipe once you know the 3pl preterite. The only outright irregular ones in this supplementary list are caber (stem couber-) and crer (which is regular but worth noting). The others fit the standard pattern.
A consolidated cheat-sheet
For quick reference, here is the 1sg future subjunctive of every irregular verb you are likely to encounter in European Portuguese:
| Verb | Meaning | 1sg future subj. |
|---|---|---|
| ser | to be | for |
| ir | to go | for |
| ter | to have | tiver |
| estar | to be (state) | estiver |
| poder | to be able | puder |
| querer | to want | quiser |
| saber | to know | souber |
| fazer | to do/make | fizer |
| dizer | to say | disser |
| trazer | to bring | trouxer |
| ver | to see | vir |
| vir | to come | vier |
| pôr | to put | puser |
| dar | to give | der |
| haver | there to be | houver |
| caber | to fit | couber |
Daily-life examples
To cement the sound of these forms, here are sentences you will likely produce or hear regularly once your Portuguese is at a B1 level or above.
Quando eu souber, digo-te imediatamente.
When I know, I'll tell you right away.
Se puderes, passa cá em casa depois do trabalho.
If you can, come by after work.
Assim que tiveres um minuto, liga-me.
As soon as you have a minute, call me.
Enquanto estiver a cozinhar, toma conta do bebé.
While I'm cooking, watch the baby.
Quando vieres jantar, traz uma garrafa de vinho.
When you come to dinner, bring a bottle of wine.
Se virmos a chuva chegar, fechamos as janelas.
If we see the rain coming, we'll close the windows.
Quem quiser boleia, que me diga até às seis.
Whoever wants a ride, tell me by six.
Se for preciso, eu empresto-te o dinheiro.
If it's necessary, I'll lend you the money.
Quando o João fizer anos, vamos fazer-lhe uma festa surpresa.
When João has his birthday, we're going to throw him a surprise party.
Se ele disser que não pode, marcamos para outro dia.
If he says he can't, we'll schedule another day.
Compound forms: future perfect subjunctive
Since ter is the auxiliary for all compound tenses, its future subjunctive tiver combines with a past participle to form the future perfect subjunctive (futuro perfeito do conjuntivo) — used for an event that will be completed before another future event.
Quando tiver acabado o relatório, vou descansar.
When I've finished the report, I'm going to rest.
Se até amanhã não tiverem respondido, voltamos a ligar.
If by tomorrow they haven't replied, we'll call again.
Assim que tivermos comprado o carro, fazemos uma viagem.
As soon as we've bought the car, we'll take a trip.
This compound tense does not need its own irregular stems — it is always tiver + past participle. But the regular tiver stem is the gateway, which is why learning ter in the future subjunctive has outsize value.
Common Mistakes
❌ Se eu serei rico, compro um barco.
Incorrect — future indicative after *se*.
✅ Se eu for rico, compro um barco.
If I'm rich, I'll buy a boat. (ser)
After se + realistic future condition, use the future subjunctive. The form for (from ser) is one of the most common irregulars.
❌ Quando eu verei o João, dou-lhe o recado.
Incorrect — future indicative after *quando*.
✅ Quando eu vir o João, dou-lhe o recado.
When I see João, I'll give him the message. (ver)
Vir as future subjunctive of ver causes a lot of initial hesitation. Accept it: when you see vir after quando/se/assim que and the context is about seeing, it is the future subjunctive.
❌ Quando ele vir a casa, mostro-lhe o jardim.
Ambiguous unless you're deliberately talking about seeing, but most likely you meant 'to come'.
✅ Quando ele vier a casa, mostro-lhe o jardim.
When he comes to my place, I'll show him the garden. (vir, to come)
To mean "come," use vier (with -ie-), not vir. This is the most slippery pair in the whole irregular set.
❌ Se tu saberes a resposta, diz-me.
Incorrect — the stem for *saber* is irregular: *souber-*, not *saber-*.
✅ Se tu souberes a resposta, diz-me.
If you know the answer, tell me.
The future subjunctive is always built from the 3pl preterite stem. Saber's preterite is soube / souberam, so the future subjunctive stem is souber-, not saber-.
❌ Quando o menino crescerá, vai entender.
Mixed tenses — future indicative after *quando*.
✅ Quando o menino crescer, vai entender.
When the boy grows up, he'll understand.
Regular verb (crescer → cresceram → crescer-). But the error pattern is the same as with irregular verbs — always the future subjunctive after quando referring to a future event.
❌ Se ele traria os bilhetes, podíamos entrar.
Mixed conditional forms — this sentence mixes type 1 and type 2 structures incoherently.
✅ Se ele trouxer os bilhetes, podemos entrar.
If he brings the tickets, we can go in. (realistic future — type 1)
✅ Se ele trouxesse os bilhetes, podíamos entrar.
If he were to bring the tickets, we could go in. (hypothetical — type 2)
Match tenses. Realistic future → future subjunctive + present indicative. Hypothetical → imperfect subjunctive + conditional or imperfect indicative.
❌ Se houvem problemas, liga-me.
Incorrect form — *houver* is the impersonal singular, or *houverem* for plural subjects.
✅ Se houver problemas, liga-me.
If there are problems, call me.
Haver in the "there is / there are" sense is used in the singular regardless of what follows (há problemas, havia problemas, houver problemas — always singular). Do not try to pluralise it.
Key takeaways
- Irregular future subjunctive stems are inherited directly from irregular 3pl preterite forms. Once you know the preterite stem, you know the future subjunctive stem.
- The big eight to memorise first: for (ser/ir), tiver (ter), estiver (estar), puder (poder), quiser (querer), souber (saber), fizer (fazer), disser (dizer).
- Ser and ir share the form for — context always resolves.
- Ver → vir (same spelling as to come) and vir → vier. Memorise both to avoid the classic ver/vir confusion.
- Tiver + past participle forms the future perfect subjunctive for completed-before-future actions.
- Regardless of regularity, the endings are always -, -es, -, -mos, -em on the preterite stem.
- Every irregular future subjunctive in Portuguese is in one of these paradigms; there are no exceptions, no additional surprises.
With this page, plus overview and regular forms, you now have the full future subjunctive in your grasp. Go back and re-read the overview once you have drilled these paradigms — the trigger list will feel much more accessible with the forms now concrete.
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.
- Preterite of Ser and IrA2 — The identical preterite forms of ser and ir
- Preterite of TerA2 — The verb ter in the preterite
- Preterite of VirA2 — The verb vir in the preterite
- Preterite of PôrB1 — The verb pôr in the preterite