Infinitives are supposed to be the form that does not conjugate — to eat, to go, one shape regardless of who is doing it. Portuguese disagrees. It has an infinitivo pessoal, an infinitive that takes person endings, and it is one of the few features that Portuguese has and Spanish simply lacks.
The forms
Take the plain infinitive and add endings directly to it. No stem change, no irregularity — including for verbs that are irregular everywhere else.
| Person | falar (speak) | comer (eat) | partir (leave) |
|---|---|---|---|
| eu | falar | comer | partir |
| tu | falares | comeres | partires |
| ele / ela | falar | comer | partir |
| nós | falarmos | comermos | partirmos |
| vocês | falarem | comerem | partirem |
| eles / elas | falarem | comerem | partirem |
Four endings total: nothing, -es, -mos, -em. And the irregular verbs behave: ser gives sermos, ter gives termos, fazer gives fazermos. This is comfortably the easiest conjugation in the language.
What it is for
It lets a subordinate clause carry its own subject without switching to the subjunctive. Compare:
| Portuguese | English |
|---|---|
| É importante estudar. | It is important to study. (in general) |
| É importante estudarmos. | It is important that we study. |
| É importante estudarem. | It is important that they study. |
One suffix replaces an entire subordinate clause. Spanish must say Es importante que estudiemos, with a conjunction and a subjunctive; Portuguese folds it into the verb.
This is the standard Portuguese-versus-Spanish exam question. The two languages are close enough that learners of one assume structures transfer. This one does not — Spanish has no equivalent, and the reflex to insert que plus a subjunctive is exactly what marks a Spanish speaker writing Portuguese.
Where it shows up
Most often after prepositions, which is where the subject-clarifying job matters most.
| Portuguese | English |
|---|---|
| Saímos antes de eles chegarem. | We left before they arrived. |
| Comprei o livro para tu leres. | I bought the book for you to read. |
| Apesar de estarmos cansados, continuámos. | Although we were tired, we continued. |
| Depois de saírem, fechámos a porta. | After they left, we closed the door. |
| É difícil trabalharmos juntos. | It is hard for us to work together. |
In each case the preposition takes an infinitive, and the ending supplies the subject that would otherwise be missing or ambiguous.
When to leave it plain
If the subject is the same as the main verb's and nothing is ambiguous, the plain infinitive is normal:
| Portuguese | Note |
|---|---|
| Quero comer. | same subject — plain infinitive |
| Queremos comer. | still plain; comermos would be heavy |
| Antes de sairmos, comemos. | subject worth marking — personal |
Native usage tolerates a fair amount of latitude in the middle ground, and both versions are often acceptable. The clear cases are the ones that matter: two different subjects means personal infinitive, and shared subject with no ambiguity means plain.
Do not confuse it with the future subjunctive
Portuguese also has a future subjunctive, which for regular verbs looks identical to the personal infinitive. They diverge on irregular verbs, and that is how you tell them apart:
| Verb | Personal infinitive | Future subjunctive |
|---|---|---|
| falar | falarmos | falarmos |
| ser | sermos | formos |
| ter | termos | tivermos |
| fazer | fazermos | fizermos |
Se formos means "if we go"; para sermos means "for us to be". The context separates them reliably — the future subjunctive follows se and quando, the personal infinitive follows prepositions.
Worth the effort
For a form with four endings and no irregulars, the personal infinitive buys a great deal. It lets you express subject-changing subordinate clauses without the subjunctive, it appears constantly in written Portuguese, and using it correctly is one of the fastest ways to stop sounding like a Spanish speaker improvising.
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Open the dictionary appFrequently asked questions
Does Spanish have a personal infinitive?
No, and it is one of the clearest structural differences between the two languages. Where Portuguese conjugates the infinitive, Spanish uses a subjunctive clause instead — para que nosotros comamos against Portuguese para comermos.
Is the personal infinitive used in Brazil as well as Portugal?
Yes, in both, and in speech as well as writing. Brazilian Portuguese uses it slightly less in casual registers, where a subjunctive clause sometimes appears instead, but it is entirely standard in both varieties.
How do I know when to use the personal infinitive rather than the plain one?
When the infinitive's subject differs from the main verb's subject, or when naming it prevents ambiguity. If both verbs share a subject and no confusion is possible, the plain infinitive is normal and adding endings sounds heavy.