Indicative vs Subjunctive: Decision Guide | Portuguese (Brazil) Grammar

The single biggest decision in Portuguese grammar is mood: do you use the indicative or the subjunctive? English barely has a subjunctive ("I insist that he be present", "if I were you"), so English speakers have no instinct for it and tend to default to the indicative everywhere. This page gives you one organizing principle — the assertion test — plus the trigger lists and the famous negation flip, so you can predict the right mood even in sentences you have never seen.

The core principle: assertion vs non-assertion

Everything reduces to one question: are you asserting that something is real?

Indicative = you are presenting the action as a fact, certainty, or something you assert to be true — it belongs to the world of reality. Use it for knowledge, statements, and reports.
Subjunctive = you are not asserting reality. The action lives in the realm of desire, doubt, emotion, hypothesis, or the not-yet-real. Use it for what you want, doubt, fear, hope, or merely suppose.

Sei que ele vem amanhã.

I know he's coming tomorrow.

Quero que ele venha amanhã.

I want him to come tomorrow.

In the first sentence you assert a fact you know — indicative vem. In the second you express a desire, not a fact — subjunctive venha. The coming is real in one and merely wished-for in the other. That contrast is the whole subjunctive in miniature.

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The assertion test: "Am I stating this as true, or am I wanting / doubting / supposing it?" Stating true → indicative. Wanting, doubting, fearing, supposing → subjunctive.

Indicative triggers — when you assert reality

Use the indicative after expressions of knowledge, certainty, and assertion. The matrix clause vouches for the truth of what follows:

sei que… (I know that)
é verdade que… / é certo que… / é óbvio que… (it's true/certain/obvious that)
acho que… / penso que… / acredito que… (I think/believe that — affirmative)
percebo que… / vejo que… / notei que… (I notice/see that)

É verdade que a vida está cara.

It's true that life is expensive.

Acho que ela já chegou.

I think she's already arrived.

Tenho certeza de que vai dar tudo certo.

I'm sure everything's going to work out.

Even though "I think" sounds tentative in English, affirmative acho que in Portuguese still treats the content as something you are putting forward as basically true — so it takes the indicative. (We'll see what happens when you negate it below.)

Subjunctive triggers — when reality is suspended

Use the subjunctive when the matrix clause expresses desire, doubt, emotion, possibility, or unreality. Memorizing the broad categories lets you generalize:

Desire / wish / request: querer que, desejar que, esperar que, pedir que, preferir que

Espero que você se sinta melhor logo.

I hope you feel better soon.

Doubt / denial: duvidar que, não acreditar que, negar que, é possível que, é improvável que

Duvido que ele se lembre de mim.

I doubt he remembers me.

Emotion / reaction: alegrar-se que, lamentar que, é uma pena que, é bom que, ter medo de que

É uma pena que você não possa ficar mais.

It's a shame you can't stay longer.

Possibility adverb — talvez: talvez ("maybe") normally takes the subjunctive, because "maybe" by definition withholds assertion.

Talvez ela venha, talvez não.

Maybe she'll come, maybe not.

Concession / purpose conjunctions: embora, ainda que, para que, a menos que, antes que

Embora seja caro, vale a pena.

Although it's expensive, it's worth it.

Hypothetical / counterfactual (imperfect subjunctive): the "if" clause of an unreal condition.

Se eu fosse você, aceitaria a proposta.

If I were you, I'd accept the offer.

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A useful umbrella: WEIRDO — Wishes, Emotions, Impersonal expressions of opinion, Requests/recommendations, Doubt, and the special Ojalá-type words (here talvez, tomara que, oxalá). Each one withholds the assertion of fact, which is why each one triggers the subjunctive.

The negation flip — the most useful single trick

This is where the assertion principle pays off dramatically. Verbs of thinking and believing take the indicative when affirmative (you assert the content) but flip to the subjunctive when negated (negating belief removes the assertion):

Acho que ele vem.

I think he's coming.

Não acho que ele venha.

I don't think he's coming.

The same flip applies to acreditar, crer, parecer, and é certo que / não é certo que:

É certo que ela aceita o cargo.

It's certain she'll accept the position.

Não é certo que ela aceite o cargo.

It's not certain she'll accept the position.

Why does this happen? Because negating "I think it's true" leaves the truth of the embedded clause unasserted — you are no longer vouching for it. Reality is suspended again, so the subjunctive returns. This is the assertion test doing exactly what it promises.

A flowchart for the choice

Is the verb in the dependent clause something you state as a fact / know to be true? → Indicative.
Does the main clause express want, doubt, emotion, or a "maybe / although / so that"? → Subjunctive.
Is it an affirmative "I think / it's certain"? → Indicative. Negated? → Subjunctive.
Is it an unreal "if" (if I were…, if it rained…)? → Imperfect subjunctive.

Decision summary

Trigger	Mood	Example
sei que, é verdade que	indicative	sei que vem
acho que (affirmative)	indicative	acho que vem
não acho que (negated)	subjunctive	não acho que venha
quero que, espero que, pedir que	subjunctive	quero que venha
duvido que, é possível que	subjunctive	duvido que venha
é uma pena que, alegro-me que	subjunctive	é pena que não venha
talvez, embora, para que	subjunctive	talvez venha
se (unreal condition)	imperfect subjunctive	se viesse

Common Mistakes

English speakers' errors here nearly all stem from defaulting to the indicative, since English rarely flags non-assertion morphologically.

❌ Quero que você vem comigo.

Incorrect — desire requires the subjunctive.

✅ Quero que você venha comigo.

I want you to come with me.

❌ Duvido que ele sabe a resposta.

Incorrect — doubt requires the subjunctive.

✅ Duvido que ele saiba a resposta.

I doubt he knows the answer.

❌ Talvez ela está em casa.

Incorrect — 'talvez' normally takes the subjunctive.

✅ Talvez ela esteja em casa.

Maybe she's at home.

❌ Não acho que ele tem razão.

Incorrect — negated 'achar' flips to the subjunctive.

✅ Não acho que ele tenha razão.

I don't think he's right.

❌ Embora é difícil, vou tentar.

Incorrect — 'embora' (although) requires the subjunctive.

✅ Embora seja difícil, vou tentar.

Although it's hard, I'm going to try.

Key Takeaways

The whole choice is assertion: stating something as real → indicative; wanting, doubting, fearing, or supposing it → subjunctive.
Affirmative verbs of belief (acho que, é certo que) take the indicative; negating them flips to the subjunctive.
Memorize the trigger categories (desire, doubt, emotion, concession/purpose, talvez, unreal se) so you can predict the mood in new sentences.
English's near-absent subjunctive makes the indicative the trap default — when a sentence is about a wish or doubt, slow down and switch moods.

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