A2 · Verbs
Tener que, deber, hay que, necesitar
Tener que does most of the work in speech. Deber is heavier and more moral, and it also has a second life meaning must be, as in a guess. Hay que has no subject at all, which makes it the polite way to say something needs doing without pointing at anyone. And the trap: no tener que and no deber do not mean the same thing — one removes an obligation, the other creates a prohibition.
Everyday, with a person
- tener que + infinitivo — Tengo que salir.
- necesitar + infinitivo — Necesito dormir más.
- deber + infinitivo — Debo llamar a mi madre.
- deberías + infinitivo — Deberías descansar.
Impersonal, no subject
- hay que + infinitivo — Hay que llegar temprano.
- se debe + infinitivo — No se debe fumar aquí.
- es necesario + infinitivo — Es necesario reservar.
- hace falta + infinitivo — Hace falta hablar con él.
Which one, and when
| Structure | Force | Example |
|---|---|---|
| tener que | the everyday obligation, from circumstances | Tengo que trabajar el sábado. |
| deber | a duty, something right or expected | Debemos respetar el horario. |
| deberías | advice, softer than deber | Deberías ir al médico. |
| hay que | impersonal: it simply must be done | Hay que reservar con dos días. |
| necesitar | a need rather than a duty | Necesito descansar. |
| hace falta | the same as necesitar, impersonal | No hace falta traer nada. |
The trap: no tener que and no deber
These look like a pair and are not. One says the obligation does not exist; the other says the action is forbidden. English has the same split between do not have to and must not, and it is exactly where students transfer the wrong one.
- No tienes que venir.You do not have to come. · it is up to you
- No debes venir.You must not come. · do not do it
- No hace falta traer nada.There is no need to bring anything. · like no tienes que
- No se debe fumar aquí.Smoking is not allowed here. · like no debes
Deber de: a guess, not a duty
With de, deber stops meaning obligation and starts meaning probability. Careful in speech: many native speakers drop the de, so context decides.
- Debe de estar en casa.He must be at home. · a deduction
- Debe estar en casa.He must be at home, or he ought to be at home. · both readings possible
- Debe llegar a las ocho.He is supposed to arrive at eight. · obligation
What follows each one
All four take an infinitive. Necesitar is the only one that also takes a plain noun.
- Tengo que un café — wrong. Necesito un café — right.
- Necesito dormir. Necesito ocho horas. Both fine.
- Hay que paciencia — wrong. Hace falta paciencia — right.
- Debo dinero a Ana — right, but here deber means to owe, not must.
In the past
The preterite and the imperfect split these the way they split everything else: whether you did it or only had to.
- Tuve que salir corriendo.I had to rush out. · and I did
- Tenía que estudiar, pero salí.I was supposed to study, but I went out. · and I did not
- Había que reservar.You had to book. · impersonal
Mistakes to avoid
Tengo que un médico.
Necesito un médico.
Only necesitar takes a bare noun.
No tienes que fumar aquí.
No debes fumar aquí.
No tener que removes an obligation; a prohibition needs no deber.
Hay que yo llegar temprano.
Tengo que llegar temprano.
Hay que never takes a subject.
Debo de llamar a mi jefe.
Debo llamar a mi jefe.
Deber de is a guess, not a duty.
Tengo que de salir.
Tengo que salir.
Tener que takes the infinitive directly.
Watch out
Tener que is far more common than deber in everyday speech. If you are unsure which sounds natural, tener que is almost always the safe choice; deber can sound preachy in casual conversation.
Try it
___ salir ahora o pierdo el tren.
En este edificio ___ reciclar la basura.
No ___ traer nada, ya tengo todo.
No ___ tocar eso, es peligroso.
___ un descanso, llevo cuatro horas aquí.
No contesta. ___ estar en clase.