deber vs deber de, haber de, tener que: modal nuance
Obligation, advice and deduction: debes, debe de ser, he de reconocer, no tienes que, podrías haber.
Part of the free C2 Spanish course. Press the speaker next to an example to hear it.
Spanish has several verbs for must, should and have to, and they are not interchangeable. The key split is between obligation (what someone has to do) and deduction (what is probably true).
deber + infinitive: obligation
Deber without a preposition expresses a moral or general obligation: must, should.
- Debes devolverle el dinero cuanto antes.You must pay him back as soon as possible.
- No debes conducir después de beber.You mustn't drive after drinking.
deber de + infinitive: deduction
Deber de expresses a supposition: it must be, it's probably.
- Deben de ser más de las doce, porque ya han cerrado el bar.It must be past twelve, because they've already closed the bar.
The norm (RAE) is strict in one direction: deber de for obligation (Debes de estudiar más) is non-standard. In the other direction, deber alone for deduction (Debe ser su hermano) is accepted.
Softened advice and reproach
The conditional softens advice: deberías (or the literary debieras). With a perfect infinitive it becomes a reproach about the past. Poder does the same.
- Deberías haberme llamado antes de salir.You should have called me before leaving.
- Podrías haberme avisado de que venías.You could have told me you were coming.
tener que: necessity and strong deduction
Tener que is the everyday have to (Obligation: tener que, hay que). It also expresses a confident deduction, stronger than deber de.
- La luz está encendida, así que tiene que estar en casa.The light is on, so she must be at home.
In the past: Tuvo que llover mucho anoche = It must have rained a lot last night.
The negative trap
| Spanish | Meaning |
|---|---|
| No tienes que venir. | You don't have to come. |
| No debes venir. | You mustn't come. |
| No hay que gritar. | There's no need to shout, or one shouldn't shout. |
- No tienes que venir si no quieres.You don't have to come if you don't want to.
haber de + infinitive
In Spain, haber de is formal or literary obligation, often with verbs of saying: he de reconocer, has de saber. In Mexico and Central America, ha de is an everyday way to make a guess.
- He de reconocer que me equivoqué.I must admit that I was wrong.
- Has de saber que aquí nadie regala nada.You should know that nobody gives anything away here.
- Ha de estar cansado después del viaje.He must be tired after the trip.
For guesses with the future (Serán las tres), see The future for guesses: Serán las diez.
Latin America
Deber de and tener que work the same way. Haber de for probability is everyday speech in Mexico (Ha de ser difícil). Debiste llamar (you should have called) is very common in Latin America; in Spain it is also heard, but deberías haber llamado or tendrías que haber llamado are more usual.
Common mistakes
Debes de estudiar másfor advice: obligation takes plain deber.No tienes que fumar aquíto forbid: that means you don't have to; say No debes fumar aquí or No se puede fumar aquí.Debería llamarte ayer: a past reproach needs the perfect infinitive, Debería haberte llamado ayer.Ha que esperar: impersonal obligation is hay que; haber de needs a person (he de esperar).- Reading debe de ser as an order: it is a guess.
Practice
- El teléfono no deja de sonar; _____ ser algo urgente.Options: debe de · debes · tiene de · ha que
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debe de
- Los alumnos _____ entregar el trabajo el lunes.Options: deben · deben de · han que · tienen de
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deben — Obligation: plain deber. Deber de for obligation is non-standard.
- 'No tienes que pagar' means:Options: You don't have to pay. · You mustn't pay. · You must pay. · You probably haven't paid.
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You don't have to pay. — Negated tener que removes the necessity; it does not forbid.
- Softened advice. _____ (deber, tú) descansar más.
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Deberías