Must, Have To, Ought: Expressions of Obligation

To express the general idea of one should, one must or it is necessary, use the construction hay que + infinitive:

  • Hay que estudiar -- One must/should study, it is necessary to study


To express the idea that someone should/must do something, use a form of tener que:

  • Tengo que estudiar -- I should/must study


Another option is to use a form of deber -- should/must:

  • Debo estudiar -- I should/must study


The present indicative conjugations of tener que and deber are:

yotengo quedebo
tútienes quedebes
él/ella, Ud.tiene quedebe
nosotros/astenemos que      debemos
vosotros/astenéis quedebéis
ellos/ellas, Uds.      tienen quedeben


Another, less common, option is haber de + infinitive:

  • Hemos de escribir un informe -- We must write a report


The present indicative conjugation of haber de is:

yohe de
túhas de
él, ella, Ud.ha de
nosotros/ashemos de
vosotros/ashabéis de
ellos/ellas, Uds.      han de


Tener que, deber and haber de can be conjugated in different tenses and moods to talk about obligation in the past, present or future:

  • Nosotros teníamos que estudiar -- We had to study.
    Ellos debieran haber comido más -- They should have eaten more.
    Habremos de ir al funeral -- We will have to go to the funeral.
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