In English we think of the infinitive as being "to" + action. E.g. "to eat".

There are cases where we use a verb followed directly by the infinitive.

E.g. "quiero comer"

quiero = I want
comer = to eat
quiero comer = I want to eat

However there are also many cases where we put "a" before the second verb.

E.g. "voy a comer" or "empiezo a comer"

empiezo = I start
a = to
comer = to eat
empiezo a comer = I start (to) to eat

Are there rules about when to include the "a" when to leave it out?

1 Answer 1


"A" precedes the following verb most of all in "perífrasis verbales". A lot of "perífrasis verbales" require a preposition (a, de...) or some other conjunction (like que, in tengo que). Some examples are:

  • Empezar/comenzar/iniciar/principiar a [verbo]: empiezo a comer
  • Ir a [verbo]: voy a comer
  • Ponerse a [verbo]: me pongo a comer
  • Volver a [verbo]: vuelvo a comer
  • Llegar a [verbo]: llego a comer

However, some don't. Some "perífrasis verbales" that don't require an "a" are:

  • Deber [verbo]: debo comer
  • Soler [verbo]: suelo comer
  • Poder [verbo]: puedo comer

There are also certain "perífrasis verbales" that take the gerund form of the verb. Almost none of them require the "a":

  • Estar [verbo]: estoy comiendo
  • Seguir [verbo]: sigo comiendo
  • Continuar [verbo]: continúo comiendo
  • Llevar [verbo]: llevo comiendo [una hora]

"A" doesn't precede the following verb most of all when the verb can be replaced by a pronoun (i.e., when it's a subject or a direct object):

  • Quiero comer — "comer" is a DO, and so it can be replaced by "eso": quiero eso
  • Me gusta comer — "comer" is the subject, and so it can be replaced by "eso": me gusta eso
  • Merezco comer — "comer" is a DO, and so it can be replaced by "eso": merezco eso
  • Conviene comer — "comer" is the subject, so it can be reaplaced by "eso": conviene eso

Look how the replacement by "eso" doesn't work with the "perífrasis verbales" cited above:

  • Empiezo a eso (wrong).
  • Voy a eso (wrong).
  • Me pongo a eso (wrong).
  • Vuelvo a eso (wrong).
  • Llego a eso (wrong).
  • Debo eso (wrong).
  • Suelo eso (wrong).
  • Puedo eso (wrong).
  • Estoy eso (wrong).
  • Sigo eso (wrong).
  • Continúo eso (wrong).
  • Llevo eso (wrong).

Although some instances with "eso/ello" instead of the verb in "perífrasis verbales" are idiomatic (such as "ponte a ello", "a eso vengo" or "ni a eso llego"), they are at least obscure from a grammatical point of view.

Bottom line: if you can susbstitute the verb by "eso", don't use "a". If you can't, use "a". If you do this, you will be right 3 out of 4 of the times. Three exceptions are "soler", "deber" and "poder", which don't require "a" even though you can't substitute the verb by "eso". Never use "a" before a gerund.

  • Could someone please explain what a gerund is? My understanding is that a gerund is a verb ending in -ing that you could replace with a noun (such as eso). For example (what you used above): estoy comiendo.
    – iamcam
    Jan 3, 2016 at 1:36
  • 2
    A gerund in Spanish ends with -ando/-endo. In English, gerunds can work as a noun, but in Spanish they can't. A gerund is only used in Spanish in continuous tenses (estoy comiendo) and as an adverb indicating the way something is done (ven corriendo). Unlike English, you could never replace a gerund with a noun or pronoun ("eso") in Spanish.
    – Yay
    Jan 3, 2016 at 10:49

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