Complement Clauses (Que + Verb)

A complement clause is a full subordinate clause — introduced by que — that plays the grammatical role of a noun inside a larger sentence. Think of it as a clause doing the job of a noun phrase: it can be a subject, a direct object, or the complement of a noun, adjective, or preposition.

In Creo que viene (I believe he's coming), the clause que viene is the direct object of creo — it answers what do I believe?. Complement clauses are everywhere in Spanish, and learning to build them precisely is essential for fluent expression.

Complements as Objects

The most common use of a complement clause is as the direct object of a verb of thinking, saying, feeling, or wanting.

In each case, the whole que clause is what's being believed, said, or known. You could replace it with a simple noun: Creo eso (I believe that), Dijo la verdad (He said the truth), Sé tu nombre (I know your name).

Complements as Subjects

A que clause can also be the subject of a sentence — typically one using es or another linking verb followed by an adjective.

The subject of es importante is the clause que estudies — studying is what's important. Notice that Spanish uses no dummy it at the start of the sentence the way English does.

Complements After Nouns: De Que

When a complement clause follows a noun, the connector is de que, not just que. This is because the underlying structure is noun + de + noun, and the noun slot is replaced by a clause.

The pattern is noun + de que + clause. Dropping the de (saying la idea que es una trampa) is a very common error and is considered incorrect in careful Spanish — it's called queísmo.

Complements After Adjectives

Adjectives that normally take de before a noun also take de que before a clause.

The preposition that the adjective governs (de in these cases) stays in place, and que follows it. Other prepositions work similarly: cansado de que, harto de que, dispuesto a que.

Choice of Mood: Indicative vs. Subjunctive

The mood of the verb inside a complement clause depends on the main clause — specifically, on what kind of meaning the main clause expresses. This is one of the richest areas of Spanish grammar. See Subjunctive vs. Indicative for the full picture.

Indicative for Facts and Belief

When the main clause asserts something as fact, the complement clause uses the indicative.

Verbs like creer, saber, decir, pensar, and expressions like es verdad que, es obvio que, está claro que all commit the speaker to the truth of the complement, so they take the indicative.

Subjunctive for Doubt, Wish, and Emotion

When the main clause expresses doubt, desire, emotion, or a non-committal evaluation, the complement clause takes the subjunctive.

Notice that negating creer flips the mood: creo que tiene (indicative, fact) vs. no creo que tenga (subjunctive, doubt).

Dropping Que: Not Allowed

In English, we routinely drop the complementizer that: I think he's coming is perfectly fine. Spanish does not allow this. The que is mandatory.

Creo viene and Dijo vendría are ungrammatical. Leaving out que is one of the most recognizable errors English speakers make in Spanish. Always include it, even when it feels redundant.

Queísmo and Dequeísmo

Two common native-speaker errors are worth knowing because they show where the system is subtle:

• Queísmo: dropping a required de before que. Me alegro que vengas is incorrect — it should be Me alegro de que vengas.
• Dequeísmo: inserting an unnecessary de before que. Creo de que viene is incorrect — it should be Creo que viene.

The test: replace the clause with a simple noun or pronoun. If you would say Me alegro de eso, then you need de que. If you would say Creo eso (without de), then it's just que.

Complements in Questions and Commands

Complement clauses can also follow verbs of asking and commanding. The embedded clause typically uses the subjunctive for commands and requests.

Verbs of asking a question embed the question directly with si (for yes/no) or a question word, without que:

Where to Go Next

Complement clauses are fundamental building blocks of Spanish sentences. To master the mood choice inside them, study Subjunctive vs. Indicative. For the bigger picture of how all subordinate clauses fit together, review Subordinate Clauses Overview. For how object pronouns behave across complex verb constructions, continue to Clitic Climbing.