Personal Infinitive After Prepositions

Imagine you want to say "for us to eat." In English, the word "eat" does not change. In Spanish or French, it stays as the impersonal infinitive too. But in Portuguese, we attach a little tail to the verb. This tail tells us that "we" are the ones doing the eating. This pattern is most common after prepositions. Prepositions are small but mighty words like para, sem, por, or até. When one of these words shows up, it often triggers the personal infinitive. You use it when the verb has a specific subject. It helps avoid confusion. If you just say the basic infinitive, people might not know who you are talking about. Adding the personal ending clears the air immediately. It is efficient and elegant.

1. 1Building the personal infinitive is surprisingly easy. You do not need to memorize a whole new set of irregular stems. You just take the standard infinitive and add specific endings. Here is the step-by-step process:
2. 2Start with the dictionary form of the verb (e.g., falar, comer, partir).
3. 3For eu, você, ele, and ela, you add nothing. The verb stays the same.
4. 4For tu, you add -es to the end. So falar becomes falares.
5. 5For nós, you add -mos. So comer becomes comermos.
6. 6For vós (rare but good for your ego), you add -des. So partir becomes partirdes.
7. 7For vocês, eles, and elas, you add -em. So falar becomes falarem.
8. 8Notice how the stem never changes. Even irregular verbs like ser or ir follow this rule. Ser becomes sermos for nós. It is very predictable.

This is the most important part. You use this pattern when the subject of the infinitive is different from the main subject. Or, you use it when you simply want to emphasize who is doing what. Let’s look at some real-world scenarios.

Scenario 1: Ordering food. You might say, "Eu trouxe este vinho para nós bebermos" (I brought this wine for us to drink). Here, nós is the subject of the drinking.

Scenario 2: At a job interview. You could say, "Obrigado por vocês me receberem" (Thank you for receiving me).

Scenario 3: Travel and directions. "É melhor esperarmos até eles chegarem" (It is better we wait until they arrive).

Common prepositions that love this pattern include:

• para (for/to)
• sem (without)
• por (for/because of)
• até (until)
• antes de (before)
• depois de (after)
• ao (upon/when)

You do not always need the personal infinitive. If the person doing the action is the same as the main verb, it is usually redundant. For example, "Eu quero comer" (I want to eat). You do not need to say "Eu quero eu comer." That would sound like you are malfunctioning. However, even in these cases, you *can* use it for extra emphasis. But generally, if the subject is obvious and shared, stick to the simple infinitive. It is faster and sounds more natural. Using it too much when it is not needed can make you sound a bit like a legal document. Nobody wants to sound like a tax return at a party.

The biggest trap is the nós form. Many people forget to add the -mos. They just say para nós falar. This sounds very "Tarzan" to a native speaker. Another common slip-up is confusing it with the future subjunctive. They look identical for regular verbs. But their jobs are totally different. The personal infinitive happens after prepositions. The future subjunctive happens after words like quando or se. Also, watch out for the eles form. Make sure you add that -em. If you say para eles fala, it sounds like a singular subject with a plural pronoun. It is like wearing one shoe. It just feels wrong.

How does this differ from the normal infinitive? The normal (impersonal) infinitive is for general statements. "Fumar é mau" (Smoking is bad). No specific person is smoking there. But "Para vocês fumarem, têm de ir lá fora" (For you to smoke, you must go outside) targets a group.

Compare it to the future subjunctive too. You use the future subjunctive for "if" or "when" scenarios: "Se eles chegarem cedo..." (If they arrive early). You use the personal infinitive for facts or results after prepositions: "Apesar de eles chegarem cedo..." (Despite them arriving early). One is about possibility; the other is about context or cause. Think of the personal infinitive as the more grounded, factual cousin.