Complement Clauses | Portuguese (Portugal) Grammar

A complement clause (oração completiva, also called a substantive clause or noun clause) is a subordinate clause that functions as a noun inside the main clause — filling the slot of a subject, a direct object, or an object of a preposition. It is the clausal equivalent of a noun phrase: everywhere sabia a verdade ("he knew the truth") works, sabia que era verdade ("he knew it was true") also works, because the subordinate clause occupies the same grammatical position as the noun phrase.

This page is the dedicated treatment of complement clauses, complementing the broader subordination overview. We go through the five major complement-clause patterns: finite que-clauses (with indicative vs subjunctive), plain infinitival complements, personal infinitival complements, embedded yes/no questions with se, and embedded wh-questions. We close with subject-raising, a structurally adjacent phenomenon that learners confuse with complement clauses. The goal is a complete, deep understanding of how Portuguese embeds one proposition inside another when the embedded proposition is playing a noun-like grammatical role.

The four positions a complement clause can fill

Before the forms, the functions. A complement clause can sit in any of the slots a noun phrase would fill.

Direct object

Sei que ela chega amanhã.

I know she's arriving tomorrow.

Disse que estava cansada.

She said she was tired.

Espero que consigam os bilhetes.

I hope they manage to get the tickets.

Here the clauses fill the direct-object slot of sei, disse, espero. Compare sei a resposta, disse a verdade, espero boas notícias — the noun phrases and the clauses occupy the same grammatical position.

Subject

Que ele já tenha chegado é uma boa notícia.

That he has already arrived is good news.

É importante que estudes para o exame.

It's important that you study for the exam.

Parece que vai chover.

It seems it's going to rain.

Subject clauses can be fronted (Que ele...) but in practice are usually extraposed to the right, with the matrix predicate (é importante, parece) preceding them.

Object of a preposition

Lembro-me de que a ajudei naquele dia.

I remember helping her that day.

Conto contigo para que a festa corra bem.

I'm counting on you so the party goes well.

Gosto de que me tratem com respeito.

I like being treated with respect.

The preposition belongs to the matrix verb's government: lembrar-se requires de, contar takes com/para, gostar takes de. When the complement is a clause, the preposition stays and que introduces the embedded clause.

Nominal complement

Some abstract nouns — o facto, a ideia, a possibilidade, a esperança — take complement clauses as their own complements. The pattern is noun + de que + clause.

Tenho a esperança de que a situação melhore.

I have the hope that the situation will improve.

O facto de que ele tenha mentido mudou tudo.

The fact that he lied changed everything.

A possibilidade de que chova preocupa-me.

The possibility that it might rain worries me.

This subtype is treated in depth on Noun Complement Clauses. Key point: the de is mandatory in the nominal pattern, because the noun governs de the way many nouns do with their complements (o medo de algo, a ideia de algo).

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A diagnostic for identifying a complement clause: can you replace the whole clause with a pronoun like isso or aquilo? If yes, it is a complement clause. Sei que ela chega → Sei isso. Works. Espero que venham → Espero isso. Works. The clause is doing the job a noun would do.

Finite que-clauses: indicative or subjunctive?

The workhorse complement is the finite que-clause. Its verb is inflected for person, tense, and mood — and the choice of mood (indicative or subjunctive) is the single most consequential grammatical decision in complement-clause syntax.

The choice is driven by the matrix predicate — the verb, adjective, or noun that selects the complement. Different semantic classes of predicates select different moods. The semantic logic is consistent across Portuguese: predicates that present their complement as factual or asserted take the indicative; predicates that present their complement as wished-for, doubted, evaluated, or possible take the subjunctive.

Indicative-selecting predicates

These present the embedded proposition as a fact or an assertion.

Semantic class	Examples
Verbs of speech	dizer, afirmar, declarar, contar, confessar, responder
Verbs of cognition	saber, pensar, achar, acreditar, crer, reconhecer, admitir
Verbs of perception	ver, ouvir, notar, reparar, descobrir, perceber
Impersonal certainty	é certo que, é verdade que, é óbvio que, é evidente que, parece que

O João disse que vai ao Porto no fim de semana.

João said he's going to Porto this weekend.

Acho que está a chover lá fora.

I think it's raining outside.

Vi que a porta estava aberta.

I saw that the door was open.

É verdade que o preço da gasolina subiu imenso.

It's true that the price of petrol has gone up a lot.

Subjunctive-selecting predicates

These present the embedded proposition as non-factual: wished, doubted, evaluated, or hypothesised.

Semantic class	Examples
Volition / desire	querer, desejar, preferir, pedir, exigir, sugerir, recomendar, permitir, proibir
Emotion / evaluation	gostar, detestar, lamentar, alegrar-se, ter medo, ter pena, estranhar
Doubt / denial	duvidar, negar, não crer, não acreditar
Necessity / importance	ser preciso, ser necessário, convir, importar, ser importante
Possibility	ser possível, ser provável, poder, talvez
Value judgement	ser bom, ser mau, ser estranho, ser triste, ser normal

Quero que venhas cedo.

I want you to come early.

Lamento que tenhas perdido o emprego.

I'm sorry you lost your job.

Duvido que ele consiga acabar a tempo.

I doubt he'll manage to finish in time.

É importante que os alunos cheguem pontualmente.

It's important that the students arrive on time.

É possível que o comboio esteja atrasado.

It's possible the train is delayed.

É estranho que ninguém tenha reparado.

It's strange that nobody noticed.

Flip-flop predicates: negation and questioning

A few matrix predicates flip from indicative to subjunctive under negation or questioning, because negation/questioning shifts the predicate's epistemic commitment from assertion to doubt.

Acho que ele vem amanhã.

I think he's coming tomorrow. (assertion — indicative)

Não acho que ele venha amanhã.

I don't think he's coming tomorrow. (doubt — subjunctive)

Achas que ele venha amanhã?

Do you think he'll come tomorrow? (questioned belief — subjunctive in careful EP)

Tenho a certeza de que ela chega hoje.

I'm sure she's arriving today. (assertion — indicative)

Não tenho a certeza de que ela chegue hoje.

I'm not sure she'll arrive today. (negated certainty — subjunctive)

The flip applies to achar, acreditar, crer, pensar, ter a certeza, and a few others. Under negation, the assertion becomes a doubt, and the subjunctive reflects that. Under questioning in careful EP, the subjunctive can appear for the same reason, though many speakers use the indicative in informal speech.

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A mnemonic for mood selection: the subjunctive marks subjectivity about the content. If the matrix predicate expresses how the speaker feels about or evaluates the proposition rather than asserting it, reach for the subjunctive. Indicative says "X is the case"; subjunctive says "I wish / doubt / evaluate X."

Non-finite complements: plain infinitive

Portuguese uses a plain infinitive as a complement when the matrix and subordinate subjects are the same. This is the economical, idiomatic choice — a finite que-clause would be redundant.

Quero ir ao cinema.

I want to go to the cinema. (same subject — infinitive)

Espero chegar a tempo.

I hope to arrive on time.

Lamento não poder ajudar-te.

I'm sorry I can't help you.

Decidi ficar em casa.

I decided to stay home.

Odeio ter de acordar cedo.

I hate having to get up early.

Some matrix verbs require a preposition before the infinitive — começar a fazer, acabar de falar, insistir em sair. The preposition belongs to the verb's government and must be supplied.

Comecei a aprender português há dois anos.

I started learning Portuguese two years ago.

Acabei de jantar agora mesmo.

I just finished dinner.

Ela insiste em pagar a conta.

She insists on paying the bill.

Non-finite complements: personal infinitive

When the matrix and subordinate subjects differ, but the subordinate subject is clear enough to manage without a full finite clause, Portuguese uses the personal infinitive (infinitivo pessoal). This is Portuguese's signature move, unavailable in Spanish, French, or Italian in this exact form.

The personal infinitive carries person-number endings:

Person	Ending	Personal infinitive of 'chegar'
eu	(zero)	chegar
tu	-es	chegares
ele / ela / você	(zero)	chegar
nós	-mos	chegarmos
eles / elas / vocês	-em	chegarem

É importante estudares todos os dias.

It's important for you to study every day.

É difícil eles aceitarem a proposta.

It's hard for them to accept the proposal.

Convém chegarmos cedo.

It's best for us to arrive early.

Depois de saíres, fecha a porta.

After you leave, close the door.

Antes de começarmos a reunião, vamos tomar um café.

Before we start the meeting, let's get a coffee.

The personal infinitive is especially common after impersonal evaluative predicates (é importante, é difícil, convém, basta) and after prepositions (antes de, depois de, para, por, sem, até). In these environments, it competes with the finite subjunctive — both are grammatical, but the personal infinitive is often more compact and more Portuguese-sounding.

Personal infinitive vs finite subjunctive

When both are grammatical, which to choose?

É importante que estudes todos os dias.

It's important that you study every day. (finite subjunctive)

É importante estudares todos os dias.

It's important for you to study every day. (personal infinitive)

Both are correct. The personal infinitive is slightly more compact and tends to sound more natural in neutral written and spoken style. The finite subjunctive is marginally more emphatic — it spells out the clause with a full tensed verb. Advanced EP leans toward the personal infinitive, especially when the subject of the subordinate clause is a pronoun or short NP.

Limits of the personal infinitive

The personal infinitive does not work as a complement of all matrix predicates. It is fine after:

Impersonal evaluative predicates (é bom, é importante, é difícil, convém)
Prepositions introducing adverbial / nominal complements (antes de, depois de, para, por, sem, até)
Certain abstract nouns (o facto de chegarmos tarde)

It is not used after:

Verbs of speech and assertion (dizer que, not dizer termos)
Verbs of knowledge (saber que, not saber sermos)
Verbs of volition where the subjects match (quero ir, not quero irmos unless the "we" is emphatic)

With volition verbs (querer, desejar) taking a different-subject complement, the finite subjunctive is the idiomatic choice:

Quero que venhas à festa. (not 'quero vires')

I want you to come to the party.

Desejo que tenhas um bom dia.

I hope you have a good day.

Saying quero vires is possible in very marked spoken Portuguese as a kind of bleached subjunctive, but it sounds colloquial to the point of non-standard; the finite que-clause is the default.

Embedded yes/no questions: se

When the embedded clause is a yes/no question — "whether" in English — Portuguese uses se to introduce it.

Perguntei se ele vinha.

I asked whether he was coming.

Não sei se está a chover lá fora.

I don't know if it's raining outside.

Gostava de saber se me podes ajudar.

I'd like to know if you can help me.

Vou verificar se a loja está aberta.

I'm going to check whether the shop is open.

Se here is not the conditional se ("if X, then Y") — it is the interrogative complementiser, introducing an embedded yes/no question. The verb in the se-clause is in the indicative, not the subjunctive (despite se's conditional use taking various moods). This is an important distinction: the same word performs two grammatical functions.

Se chover amanhã, ficamos em casa.

If it rains tomorrow, we'll stay home. (conditional se — future subjunctive)

Pergunto-me se vai chover amanhã.

I wonder if it will rain tomorrow. (embedded question se — indicative)

Embedded wh-questions

Wh-embedded questions use the same question words (o que, quem, onde, quando, como, porque, qual) but without the subject-verb inversion typical of direct questions.

Direct vs indirect

'Onde moras?' perguntou ela.

'Where do you live?' she asked. (direct)

Ela perguntou onde eu morava.

She asked where I lived. (indirect — no inversion, tense shift)

'Quem veio?' quis saber.

'Who came?' he wanted to know. (direct)

Quis saber quem tinha vindo.

He wanted to know who had come. (indirect)

Notice the structural changes in indirect questions:

No subject-verb inversion: onde moras → onde eu morava.
The question mark disappears — it's a statement that contains a question.
The tense shifts follow the rules of reported speech: present → imperfect when the matrix verb is in the past.

The o que vs que choice

In embedded questions, the interrogative pronoun for "what" is typically o que:

Não sei o que ele quer.

I don't know what he wants.

Pergunto-me o que vão decidir.

I wonder what they're going to decide.

Using just que in an embedded question (Não sei que ele quer) is ungrammatical — it would be misread as a subordinator introducing a statement, not an embedded question word. The form o que is disambiguating.

Embedded porque

The embedded interrogative "why" is por que or porque. Usage varies:

Não sei porque ele saiu.

I don't know why he left.

Quero saber por que motivo ele saiu.

I want to know for what reason he left. (more formal)

The one-word form porque is standard in embedded questions in EP. The independent noun porquê (as in o porquê — "the reason") is a different form with its own use.

Subject-raising: a complement-like but distinct construction

A few matrix verbs in Portuguese exhibit subject-raising: the embedded subject appears to "raise" to the matrix subject position, even though semantically it belongs to the embedded clause. The classic raising verb is parecer.

Parece que o João está cansado.

It seems João is tired. (impersonal parece + finite complement)

O João parece estar cansado.

João seems to be tired. (raised — João is matrix subject but is still semantically the subject of 'estar cansado')

In the second sentence, o João is the grammatical subject of parece, but it does not get its tiredness from parece — that belongs to estar cansado below. Portuguese has raised it into the matrix position without changing the semantic relationship.

Raising is distinguished from ordinary complement clauses by a couple of tests. First, the matrix verb contributes no thematic role to the raised subject — parecer does not say what o João is doing, only that something else about him is apparent. Second, raising is compatible with expletive-like extraposition (parece que...), which would not work with a true matrix subject verb.

Other raising-like verbs in Portuguese include começar a, acabar de, continuar a, which take infinitival complements with the matrix subject understood as the subject of the lower verb:

O João começou a estudar medicina.

João started studying medicine.

A Ana acabou de chegar.

Ana just arrived.

These are really aspectual verbs, not raising verbs in the formal sense, but they share the structural feature that the matrix subject is interpreted as the subject of the infinitive. Full treatment on Raising and Control.

Sequence of tenses

When the matrix verb is in a past tense, the complement-clause verb shifts accordingly. This is the Portuguese sequence-of-tenses (concordância dos tempos) system.

Matrix	Direct complement	Indirect complement
Present: diz que	present indicative: está	(no shift)
Past: disse que	present → imperfect: estava	shift
Past: disse que	perfect → pluperfect: tinha estado	shift
Past: disse que	future → conditional: estaria	shift

Ele diz que está cansado.

He says he's tired.

Ele disse que estava cansado.

He said he was tired.

Ele disse que tinha estado doente.

He said he had been sick.

Ele disse que viria amanhã.

He said he would come tomorrow.

Similar shifts apply to the subjunctive: present subjunctive → imperfect subjunctive under a past matrix.

Quero que venhas.

I want you to come.

Queria que viesses.

I wanted you to come.

Pediu que o ajudassem.

He asked them to help him.

Full details on Sequence of Tenses.

Register and complement-clause choice

Complement clauses are not register-neutral. A few patterns to know:

Plain infinitive for same-subject complements: neutral, ubiquitous. Avoid the heavy que eu vá when ir would do.
Finite subjunctive for different-subject volition/emotion: neutral in speech and writing.
Personal infinitive for different-subject impersonal predicates: somewhat more literary; more common in careful writing than casual speech.
Nominal complement with de que: formal, essayistic; in conversation, speakers often restructure to avoid it.

O facto de que o governo aprovou a lei gerou controvérsia.

The fact that the government approved the law caused controversy. (formal / written)

O facto de o governo ter aprovado a lei gerou controvérsia.

The fact that the government approved the law caused controversy. (personal infinitive alternative, often preferred in neutral style)

O governo aprovou a lei e deu polémica.

The government passed the law and it caused a stir. (colloquial restructuring — clause recast as two coordinated main clauses)

Part of advanced Portuguese is knowing which complement structure fits which register.

Common Mistakes

❌ Ela disse ela está cansada.

Incorrect — missing 'que' before the complement clause.

✅ Ela disse que está cansada.

She said she's tired.

English allows "that" to drop after verbs of speech; Portuguese does not. Dropping que is the most recognisable anglicism in Portuguese learner writing.

❌ Quero que eu vá à festa.

Ungrammatical — same subject should use the infinitive.

✅ Quero ir à festa.

I want to go to the party.

When the matrix and embedded subjects match, use the plain infinitive. A finite que-clause with coreferential subjects is ungrammatical.

❌ Antes de eles chegar, preparei tudo.

Incorrect — different subject needs personal infinitive.

✅ Antes de eles chegarem, preparei tudo.

Before they arrived, I prepared everything.

With an explicit subordinate subject, switch to the personal infinitive (chegarem) to encode it.

❌ Espero que ele vem.

Incorrect — 'esperar que' triggers the subjunctive.

✅ Espero que ele venha.

I hope he comes.

Verbs of hope, desire, emotion require the subjunctive in their complement. Using the indicative is a frequent learner error.

❌ Sei que ele venha.

Incorrect — 'saber que' takes the indicative.

✅ Sei que ele vem.

I know he's coming.

The reverse error: using the subjunctive after verbs of knowledge/assertion. Saber, dizer, ver, ouvir all take the indicative.

❌ Perguntei se ele venha.

Incorrect — embedded yes/no questions use the indicative.

✅ Perguntei se ele vinha.

I asked whether he was coming.

The interrogative se (whether) takes the indicative, with tense shift under a past matrix. The subjunctive is not an option here — confusion with conditional se produces this error.

❌ Não sei que ele quer.

Ambiguous — looks like a subordinator, not an interrogative.

✅ Não sei o que ele quer.

I don't know what he wants.

Embedded "what" is o que, not bare que. The o is disambiguating.

❌ Ela disse que viu-me.

Incorrect — subordinate clauses require proclisis.

✅ Ela disse que me viu.

She said she saw me.

Inside a que-clause, EP places the clitic before the verb. Enclisis is the main-clause default; subordinate clauses flip to proclisis.

❌ O facto que ele mentiu.

Incorrect — nominal complement requires 'de que'.

✅ O facto de que ele mentiu.

The fact that he lied.

Abstract nouns introducing complement clauses require de: o facto de que, a ideia de que, a esperança de que. Dropping de is a common English-influenced error.

Key Takeaways

A complement clause fills a noun-phrase slot: direct object, subject, object of a preposition, or complement of an abstract noun.
Finite que-clauses are the default for different-subject complements. The verb's mood (indicative or subjunctive) is driven by the matrix predicate.
Indicative after verbs of assertion, cognition, perception, and impersonal certainty. Subjunctive after volition, emotion, doubt, necessity, possibility, and value judgement.
Negation and questioning flip some matrix predicates from indicative to subjunctive (acho que vem → não acho que venha).
Same-subject complements use the plain infinitive (quero ir) — never a que-clause with coreferential subjects.
Different-subject complements of impersonal and prepositional predicates can use the personal infinitive (antes de chegarmos, é importante estudares), Portuguese's signature compact structure.
Embedded yes/no questions use se
- indicative (distinguished from conditional se); embedded wh-questions use the wh-word without subject-verb inversion.
Nominal complements of abstract nouns (o facto, a ideia, a esperança) take de que
- clause; dropping de is ungrammatical.
Sequence of tenses applies: a past matrix shifts the complement tense backward (present → imperfect, perfect → pluperfect, future → conditional).
Proclisis in subordinate clauses is automatic in EP — the clitic hops in front of the subordinate verb.