O infinitivo pessoal
Portuguese has a verb form no other major Romance language has: the infinitivo pessoal — an infinitive that conjugates for person. It's built by adding -, -es, -, -mos, -des, -em to the infinitive: falar, falares, falar, falarmos, falardes, falarem. The job: in subordinate clauses where the subject of the infinitive differs from the main subject, or where you'd otherwise have to use the conjuntivo. É melhor saíres agora = It's better for YOU to leave now. Para chegarmos a tempo, temos de partir já = For US to arrive on time, we have to leave now. It's a tense-saver — clearer than a que + conjuntivo clause, often more elegant, and absolutely native to Portuguese ears.
Formation — endings on the infinitive
Take any infinitive (regular OR irregular) and add: — (eu), -es (tu), — (ele/ela/você), -mos (nós), -des (vós, archaic), -em (eles/elas/vocês). falar → falar, falares, falar, falarmos, falardes, falarem. comer → comer, comeres, comer, comermos, comerdes, comerem. partir → partir, partires, partir, partirmos, partirdes, partirem. The 1st and 3rd person singular look identical to the impersonal infinitive (falar = falar) — context tells them apart. CRUCIALLY, the personal infinitive is REGULAR even for verbs whose conjuntivo is irregular: ser → ser, seres, ser, sermos, serdes, serem; ter → ter, teres, ter, termos, terdes, terem; ir → ir, ires, ir, irmos, irdes, irem. That's the secret of its appeal — no irregular stems to memorize. With reflexive verbs, the pronoun follows EP rules: levantarmo-nos cedo (note the -mos drops the s before -nos — phonetic adjustment).
When the subject differs — the main use
If a subordinate clause has a different subject from the main clause, the personal infinitive lets you mark that subject without a que + conjuntivo construction. É melhor (eu) sair agora is fine if the subject is eu (1sg looks like impersonal). But for clarity with other persons: É melhor saíres agora = better that YOU leave. É melhor sairmos agora = better that WE leave. É melhor saírem agora = better that THEY leave. Compare the que + conjuntivo equivalent: É melhor que saias agora — also correct, just heavier. The personal infinitive is preferred when shorter and clearer. Trick: use it whenever you can identify the subject without a finite verb. O facto de ela ter chegado tarde = the fact that she arrived late (ter in personal infinitive 3rd-sg).
After prepositions — para, sem, antes de, depois de, até
Prepositions are a perfect home for the personal infinitive, because they introduce non-finite clauses. Para chegarmos a tempo, temos de partir = (in order) for us to arrive on time. Sem ele saber = without him knowing. Antes de partires, liga-me = before you leave, call me. Depois de eles chegarem, jantamos = after they arrive, we'll have dinner. Até saírem todos, espero = until everyone leaves, I'll wait. Compare with the impersonal infinitive when the subject is the SAME as the main clause: Para CHEGAR a tempo, EU tenho de partir (same subject — impersonal) vs. Para chegarmos a tempo, ELES têm de partir (different subject — personal). The choice signals subject identity vs. difference.
After impersonal expressions — é + adjective + infinitivo
É melhor / É bom / É importante / É natural / É preciso / É necessário / É possível / É difícil + infinitive is a hugely common pattern. With no specified subject, use impersonal infinitive: É bom estudar todos os dias = it's good to study every day (general). When you DO want to specify the subject, use the personal infinitive: É bom estudarmos todos os dias = it's good for us to study every day. É importante chegarem cedo = it's important that they arrive early. É difícil ele admitir o erro = it's hard for him to admit the mistake. The alternative — que + conjuntivo — is also correct but wordier: é importante que cheguem cedo. Native EP speakers reach for the personal infinitive first; B2 learners often default to que + conjuntivo and sound less fluent.
Personal infinitive vs. conjuntivo — the choice
Many sentences allow both. Tip-the-scales rules of thumb: (1) Personal infinitive when the subject is clear from context and the construction is short. É melhor saíres > É melhor que saias. (2) Conjuntivo when the meaning is fully VOLITIONAL or expresses doubt/emotion in a way the infinitive doesn't carry. Quero que venhas (I want you to come — only conjuntivo works here, NOT quero vires). Espero que estejas bem (I hope you're well — only conjuntivo). (3) After prepositions, the personal infinitive is almost always smoother: antes de saíres > antes que saias (the preposition + infinitive is the natural pattern). (4) O facto de + personal infinitive is a fixed nominalization: o facto de teres mentido = the fact that you lied. After querer, pedir, mandar, deixar, fazer + person, the conjuntivo or accusative + infinitive wins — personal infinitive doesn't fit there directly.
Compound personal infinitive — ter + part.
Like other Portuguese tenses, the personal infinitive has a compound (perfect) form: ter in personal infinitive + past participle. Por terem chegado tarde, perderam o comboio = Because of having arrived late, they missed the train. Apesar de termos estudado, não passámos = Despite our having studied, we didn't pass. Lamento o facto de teres mentido = I regret the fact that you lied. The compound form locates the action BEFORE the main verb's time, just like English 'having + past participle'. Drill: ter, teres, ter, termos, terdes, terem + participle — ter falado, teres falado, ter falado, termos falado, terdes falado, terem falado. This compound form is heavily used in formal and written Portuguese.
Brazilian register — same form, slightly less reach
BR Portuguese has the personal infinitive identically — same forms, same uses, fully grammatical. The difference is frequency: BR speech sometimes prefers para que + conjuntivo or para + impersonal infinitive even where EP would mark the person. Para que cheguemos cedo (BR-friendly) vs. Para chegarmos cedo (both, but EP's first choice). At B2, treat the personal infinitive as a feature you should USE actively, not just recognize. It's one of the few constructions where Portuguese is clearer and shorter than its Romance neighbors — Spanish and French have to go to the subjunctive. Master the endings (-, -es, -, -mos, -des, -em), recognize the subject-mismatch trigger, and reach for it after prepositions and impersonal é + adj expressions.
