Future Subjunctive Usage Differences

Portuguese is, with its sister language Galician, one of only two living Romance languages that still use a future subjunctive as a regular tense of everyday speech. (Spanish has one, but it survives only in legal texts and set phrases — a museum exhibit rather than a working tool.) The future subjunctive is a dedicated verb form used after certain conjunctions — quando, se, enquanto, assim que, sempre que, logo que, à medida que, onde, conforme, como — when the event in the dependent clause is future from the perspective of the main clause. It is a distinctive, elegant feature of Portuguese grammar — and like so many other features, it survives in full vigour in PT-PT and has begun to erode in colloquial BR.

This page covers what the future subjunctive looks like, how it is used in each variety, and where the two varieties diverge. It is the kind of grammar point that separates serious learners from casual ones: once you have it right, your Portuguese sounds immediately more polished, and for PT-PT it is not a stylistic flourish but a basic grammatical requirement.

What is the future subjunctive?

The future subjunctive is a verb mood used in dependent clauses that refer to a future action or state. The closest English analogue is the bare present tense used after when in future-reference contexts: "I'll call you when I get home" — the verb get is not actually present, because the action hasn't happened; it is a future event seen from the main clause's perspective. Portuguese marks this distinction explicitly with a dedicated tense.

Note the critical translation correspondence: English uses the present tense (when you get, if you want, while I can); Portuguese uses the future subjunctive (chegares, quiseres, puder). This is a grammatical mismatch English-speakers need to internalise.

Forms: regular verbs

The future subjunctive has three conjugation patterns — one for each infinitive ending (-ar, -er, -ir). The distinctive feature: the form is identical to the personal infinitive for regular verbs. (For irregulars, they diverge — see below.)

-ar verbs: falar (to speak)

-er verbs: comer (to eat)

-ir verbs: partir (to leave / depart)

The pattern: the infinitive stem + personal endings (-, -es, -, -mos, -des, -em). For regular verbs, the first- and third-person singular are identical to the base infinitive — falar, comer, partir — which is why newcomers sometimes wonder whether this is even a conjugation or just a bare infinitive. It is a conjugation: the other persons distinguish themselves with endings.

Forms: irregular verbs

The irregulars are where the future subjunctive becomes distinctive, because these forms are visibly different from the infinitive. They are built from the third-person plural preterite stem — drop the -am ending of the preterite and add the future subjunctive endings.

Notice the coincidence: the future subjunctive of ver is vir, which is identical to the infinitive of vir (to come). Portuguese allows this homophone to coexist because the contexts disambiguate — quando vir o João ("when I see João," from ver) vs. quando vier o João ("when João comes," from vir, where the future subjunctive is vier). Similarly, the future subjunctive of vir is vier, which is related to but distinct from ver's future subjunctive vir.

Licensers: which conjunctions trigger it?

The future subjunctive is licensed by a specific set of subordinating conjunctions when they introduce a future-reference clause. The list is the same in both varieties — the divergence is not in which conjunctions trigger it, but in whether speakers actually use the form or substitute the indicative.

The common thread: these conjunctions can introduce clauses referring to future events. When the clause is in fact future-referring, the future subjunctive is licensed.

Past-referring uses of these conjunctions

Note that the same conjunctions can introduce past-referring clauses — quando eu era pequeno, brincava na rua ("when I was little, I played in the street"). For past, the future subjunctive is not used: the imperfect indicative (era, brincava) is the natural tense. The future subjunctive is future-specific.

The PT-PT / BR divergence

This is the core of the page. Both varieties recognise the future subjunctive as grammatical. Both varieties use it in formal writing. The divergence is in whether it is used in everyday speech — and here PT-PT and BR go different ways.

PT-PT: full usage in speech and writing

In European Portuguese, the future subjunctive is not optional. It is the required tense after future-referring quando, se, enquanto, assim que, logo que, sempre que, etc. A Portuguese 5-year-old uses it correctly. A Portuguese street vendor uses it in casual conversation. A Portuguese professor uses it in academic prose. There is no register where it is dropped.

Substituting the present indicative quando chega, se quer, se tem dinheiro sounds wrong to a Portuguese ear in these contexts. The PT-PT learner has no choice but to master the future subjunctive.

BR: regular in writing and careful speech, but often dropped colloquially

In Brazilian Portuguese, the future subjunctive is fully grammatical and universally known — every educated Brazilian knows and uses it. But in colloquial speech, especially with certain conjunctions and with você, Brazilians often substitute the present indicative for the future subjunctive.

The substitution is most common:

1. In speech, not writing. Written BR follows the PT-PT pattern: future subjunctive is required.
2. With você as the subject. Brazilian quando você chega is heard and accepted in colloquial speech; quando chegares (with tu) would sound odd anyway because tu itself is regional in BR.
3. With assim que, sempre que more than with quando, se. Even BR-colloquial speakers tend to preserve the future subjunctive after quando and se more carefully than after other conjunctions.

Formal BR writing matches PT-PT

Brazilian newspapers, academic papers, literary texts, government documents, and formal correspondence all use the future subjunctive consistently. The divergence is a register split within BR, not a grammar split between BR and PT-PT. BR colloquial speech is the only place where the future subjunctive is weakening.

A historical note: the future subjunctive in the broader Romance landscape

The future subjunctive in Portuguese descends from the Latin future perfect indicative (amavero, amaveris, amaverit...) and/or from the Latin perfect subjunctive — it is unusual that two Latin tenses merged into one Romance tense. The feature was present in early Spanish (hablare, hablares, hablare...) but died out of living Spanish by about the 18th century, surviving only in legal fossils ("si fuere necesario") and set phrases ("sea lo que fuere").

Portuguese retained the feature fully, making it today — along with Galician — the only Romance language where the future subjunctive is a living tense of everyday speech. This is a conservative feature of Portuguese, preserved because (as with hei-de, the article + possessive, and the future subjunctive itself) European Portuguese preserves more of the older system. BR, as we've seen, is in a slow drift toward simplification in speech, but this drift is partial and register-bound.

Common mistakes

Mistake 1: Using the present indicative in PT-PT where the future subjunctive is required.

Mistake 2: Using the present subjunctive instead of the future subjunctive.

Mistake 3: Using the infinitive instead of the future subjunctive.

Mistake 4: Confusing future subjunctive with personal infinitive.

The difference: the future subjunctive is for future-referring clauses after certain conjunctions like quando, se, enquanto; the personal infinitive is for uninflected infinitive clauses after prepositions or as subjects; the present subjunctive is triggered by que after verbs of desire, doubt, etc.

Mistake 5: Forgetting to use the future subjunctive for third-person singular and first-person singular (where the form looks like an infinitive).

Key takeaways

• The future subjunctive is a dedicated Portuguese tense used after certain conjunctions (quando, se, enquanto, assim que, logo que, sempre que, à medida que, etc.) when the dependent clause is future-referring.
• Regular forms are built on the infinitive stem: falar → falar, falares, falar, falarmos, falardes, falarem.
• Irregular forms use the third-person plural preterite stem: ter → tiver, fazer → fizer, ver → vir, vir → vier, pôr → puser, querer → quiser, poder → puder, ser/ir → for, dar → der, dizer → disser, haver → houver, etc.
• PT-PT uses the future subjunctive everywhere — in speech and writing, by children and professors alike. It is not optional.
• BR colloquial speech sometimes substitutes the present indicative (quando você chega) for the future subjunctive, especially with você and with certain conjunctions. BR writing and formal speech, however, follow the PT-PT pattern.
• The future subjunctive in Portuguese is one of the last surviving future subjunctives in the Romance family — Spanish has lost it in speech; Portuguese has kept it.
• For PT-PT learners, mastering the future subjunctive is not optional. Failing to use it is one of the most visible BR-trained errors.
• The forms of regular verbs in the future subjunctive look like the personal infinitive — the distinguishing feature is syntactic: future subjunctive follows a conjunction, personal infinitive follows a preposition.