Must in Spanish || How to Use Deber & Tener

Q: What’s the difference between deber and tener que in Spanish?

Deber implies a moral obligation or recommendation (“should/must”), while tener que expresses a stronger or more practical necessity (“have to/must”). Example: Debes decir la verdad. (“You must tell the truth.”) vs. Tienes que trabajar mañana. (“You have to work tomorrow.”)

Q: Can hay que also mean "must"?

Yes. Hay que is an impersonal expression used to mean "one must" or "it’s necessary to." Example: Hay que estudiar para aprobar. (“You must study to pass.”)

Q: Is deber stronger than tener que ?

Not necessarily. Deber can sound more formal or ethical , while tener que is more commonly used in everyday speech for concrete obligations.

Q: How do you express “must not” or “mustn’t” in Spanish?

Use no deber or no se debe to express prohibition. Example: No debes fumar aquí. (“You must not smoke here.”)

Q: Which form is more common in conversation: deber , tener que , or hay que ?

Tener que is the most frequently used in spoken Spanish , while deber is more formal or written , and hay que is used when the subject is general or impersonal.

Home B1 Must in Spanish

HOW TO SAY MUST IN SPANISH

Must in Spanish is expressed using verbal constructions known as perífrasis verbales, which combine auxiliary verbs with an infinitive.

While the term “must” in English indicates a strong sense of obligation and necessity, in Spanish, these characteristics are modulated depending on the verbal construction used.

DEBER + INFINITIVE

This sentence structure is used to express an obligation or duty, in the sense of an internal or moral obligation. The word deber, when used in this construction, functions as an auxiliary to the main action verb.

Although this construction expresses a strong sense of obligation, it can be softened when used in the conditional form, like for example, deberías (you should).

In this context, deber + infinitive expresses a strong recommendation or a necessity, framed more as an advisory than an imperative.

PATTERN

Deber + infinitive (unconjugated form of the main action verb)

NOTE || When the verb deber is followed by the preposition de + infinitive, it expresses an assumption or probability rather than an obligation.

Debo ser más ordenado con mis cosas.	I must be tidier with my things.
Deberemos estudiar más este semestre.	We must study more this semester.
Debes ayudar a tu hermana.	You (singular, informal) must help your sister.
Deben entrar por la puerta principal.	You (plural, formal) must enter through the front door.
Debéis conducir con cuidado cuando llueve.	You (plural, informal) must drive carefully when it rains.
Deberías pensártelo mucho antes de decidir.	You (singular, informal) should think it through carefully before deciding.

TENER QUE + INFINITIVE

The sentence structure tener que + infinitive is used to express an obligation, a necessity, or an inference based on what is considered certain. The use of tener que conveys the idea of a more pressing or unavoidable obligation than deber.

Tener que can translate to “have to” or “must”, suggesting that one is compelled or required to act due to external circumstances or necessity.

PATTERN

Tener que + infinitive (unconjugated form of the main action verb)

Tengo que irme a dormir temprano hoy.	I have to go to sleep early today.
Tienes que escribir esa carta.	You have to write that letter.
Tenemos que irnos enseguida.	We must leave right away.
Tenéis que salir de casa antes.	You (plural, informal) have to leave the house earlier.
Tienen que acabar de comer pronto.	They have to finish eating soon.
Tiene que haber sido un error.	It must have been a mistake.

HABER DE & HABER QUE

The verbal constructions haber de + infinitive and haber que + infinitive are used to express obligation, although in a distinct manner:

Haber de + infinitive is more formal and literary, expressing an inevitable sense of obligation.

Haber que + infinitive is an impersonal construction typically used to express a general necessity or obligation.

SRUCTURE 1

When expressing an obligation in contexts where inevitability is implied, the structure of the verbal construction is as follows:

PATTERN

Haber de + infinitive (unconjugated form of the main action verb)

The verb haber must be conjugated to match the subject performing the action.

Ha de hablar con dirección para ese asunto.	For that issue, you must speak with the management.
He de terminar con el trabajo hoy.	I must finish the work today.
Has de completar la solicitud.	You must complete the application.
Habéis de esperar a que acabe la función para salir.	You must wait until the show is over to leave.
Han de vaciar la sala para la próxima reunión.	You must vacate the room for the next meeting.
Hemos de intentarlo de nuevo.	We must try again.

SRUCTURE 2

When expressing general necessity or obligation, the structure of the verbal construction is as follows:

PATTERN

Haber que + infinitive (unconjugated form of the main action verb)

The verb haber remains in the impersonal form, like for example, hay que, indicating an unspecified subject.

Hay que salir temprano para no encontrar tráfico.	One has to leave early to avoid traffic.
Habrá que volver mañana.	We will have to return tomorrow.
Hay que hacer las cosas bien.	Things must be done properly.
Hay que tener en cuenta su opinión.	One must consider his/her opinion.
Hay que contribuir a los esfuerzos del equipo.	One must contribute to the efforts of the team.
Hay que estudiar para el examen.	One must study for the exam.

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FAQs

What’s the difference between deber and tener que in Spanish?

Deber implies a moral obligation or recommendation (“should/must”), while tener que expresses a stronger or more practical necessity (“have to/must”).

Example: Debes decir la verdad. (“You must tell the truth.”) vs. Tienes que trabajar mañana. (“You have to work tomorrow.”)

Can hay que also mean “must”?

Yes. Hay que is an impersonal expression used to mean “one must” or “it’s necessary to.”

Example: Hay que estudiar para aprobar. (“You must study to pass.”)

Is deber stronger than tener que?

Not necessarily.

Deber can sound more formal or ethical, while tener que is more commonly used in everyday speech for concrete obligations.

How do you express “must not” or “mustn’t” in Spanish?

Use no deber or no se debe to express prohibition.

Example: No debes fumar aquí. (“You must not smoke here.”)

Which form is more common in conversation: deber, tener que, or hay que?

Tener que is the most frequently used in spoken Spanish, while deber is more formal or written, and hay que is used when the subject is general or impersonal.

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Spanish Grammar Bank

HOW TO SAY MUST IN SPANISH

DEBER + INFINITIVE

PATTERN

TENER QUE + INFINITIVE

PATTERN

HABER DE & HABER QUE

SRUCTURE 1

PATTERN

SRUCTURE 2

PATTERN

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