Today, we focus on the usage of deber and deber de + infinitive. The two periphrasis are often used wrongly in both oral and written Spanish. Today, El Ricón del Tandem Spanish school helps you avoid any mistakes. Take a look at this short explanation! ?

Deber and deber de followed by an infinitive are two verbal periphrasis, very commonly used in Spanish. It is quite likely to find them used interchangeably or mistakenly in written texts in spoken Spanish, especially in colloquial language.

At our Spanish lessons, teachers help students learn the difference between the two periphrasis through dynamics and practical exercises.

If you also have doubts when it comes to choosing one periphrasis or another, we have good news! The answer to your questions is very simple…. take a look below!

Firstly, in Spanish grammar, both deber and deber de + infinitive are verb periphrasis. That is, a construction of two verbs that convey one inseparable idea and form a syntactic unit.
In verbal periphrasis, we find a conjugated form + an impersonal form. In some cases (as in deber de + infinitive) the two verbal forms are connected by a preposition.

Secondly, both deber and deber de + infinitive are used to express a probability. Therefore, we can use one or another when we make assumptions.
Let’s see the meaning of each one, here below

In Spanish, DEBER + Infinitive is used to:

1. To express obligation, responsibility or necessity

  • Debo enviar mi solicitud antes de las siete de la tarde = I must send my application before 7 p.m.
  • Debo hacer mis tareas esta tarde = This afternoon, I must do my l homework
  • El proyecto debe ser aprobado por todos los miembros del equipo = The project must be approved by all the team members

2. To express a probability or make an assumption

  • ¿Puedes abrir la puerta? ¿Debe ser Ana que vuelve de la universidad = Could you open the door? It mus be Ana coming from the university
  • Este paquete debe ser para ti = This box must be for you
  • Deben ser las nueve en punto = It must be 9.00 o´clock

DEBER DE + infinitive

As mentioned before, in Spanish DEBER DE + infinitive only indicates probability or assumption.
Therefore, this periphrasis only has one purpose and cannot be used to indicate obligation.

Están llamando al teléfono; debe de ser la abuela = The phone is ringing; it must be grandma
No sé dónde está exactamente el restaurante, pero debe de estar cerca de la estación de trenes = I don’t know exactly where the restaurant is; it must be close to the train station

So, to sum up, we only have to keep in mind that:

– To express probability or to make assumptions, we can use DEBER or DEBER DE (both options are correct)
– To express obligation, duty or necessity we only use DEBER

We hope this short explanation about the correct usage of deber and deber de has been useful ?

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Lastly, we remind you that our Spanish school, El Rincón del Tándem, is happy to provide Spanish lessons in Valencia, in a friendly cosy place.
Have a good day!