From time to time I've learned that the two imperfect subjunctive conjugations and the future subjunctive are formed from preterit indicative. For example: (ir/ser) fue -> fuera/fuese/fuere, or (hacer) hice -> hiciera/hiciese/hiciere.

This allows me to easily conjugate a verb into imperfect or future subjunctive tense as long as I know one of its preterit conjugations.

I wonder what the "root" of present subjunctive is. Is it (first person singular present indicative) or (3rd-singular/1st-plural/3rd-plural imperative)?

P.S. Those three imperative conjugations seems to always be from the same root. Am I right?

Editado: first person singular is yo (yo soy, yo estoy), third person singular is él/ella/ud (él es, ella tiene), first person plural is nosotros (vayámonos), third person plural is ellos/ellas/uds.

  • In general your first suggestion is correct but I cannot find an online list of the exceptions. Presumably you know that for a specific verb you can find its entry in the DLE and click on conjugar? That does not help if you are standing on a mountain top with no network coverage of course.
    – mdewey
    Jan 20, 2018 at 14:27
  • @mdewey Every decent speaker remembers a lot of conjugations for commonly used verbs, right?
    – iBug
    Jan 20, 2018 at 14:29

2 Answers 2


The stem for all conjugations of the present subjunctive is always the first-person singular of the indicative. That’s why it’s que tu hagas, since the first person singular of hacer is hag-o, and that forms the subjunctive stem.

There are, unfortunately, a lot of verbs with a stem irregularity in the first-person singular of the indicative, and thus also in all the present subjunctive forms. For example, caber has que tu quepas because of this. Really very many of those.

This is also the stem used for all imperatives save one alone. As you know, the subjunctive will have a swapped inflectional vowel compared with the indicative. The one that doesn’t work this way is the affirmative imperatives (but not the negative ones). The affirmative tú imperative is the same “stem” as the second person indicative, but chops off the final -s. It does not change the inflectional vowel to make a subjunctive the way it does for negative imperatives.

The reason it works this way is because that’s similar to how Latin did it. So for example the Latin verb amare had tu amas in the indicative and tu ames in the subjunctive, but just play ama in the tu-imperative. And yes, I deliberately picked a verb where all those things still work the same way in Spanish. But the main theme persists.

This is also why you find a similar lack of subjunctive being used in equivalent affirmative tu-imperatives in neighboring Romance languages like Portuguese or Asturian, French or Italian, Catalan or Occitan.

The thing you’re probably having trouble with is knowing which affirmative imperatives are shortened (“apocopic, apocopated”) forms. There are only a few of these, and they are common verbs. Instead of using the unchanged third-person singular for their imperative, most of these just lose the final -e as well, although there are a few extra irregularities:

  • decir: di (has a stem change and also loses the -c)
  • hacer: haz (rewrite final -c to -z after losing the -e, but that doesn't count)
  • ir: ve (very irregular: not an apocopation of va or vas)
  • poner: pon
  • salir: sal
  • ser: sé (very irregular: not an apocopation of es or eres)
  • tener: ten (notice no stem change; cf tiene)
  • venir: ven (notice no stem change; cf viene)

Formally, valer should also be added to that list making val its imperative, but you may also hear it conjugated regularly as vale.

You also do the same sort of thing with compound verbs formed from those nine I’ve just listed above, so for example interponer would just be interpón for the command.

All the others are just the normal third-personal singular in the indicative, so the form without the final -s. Even irregular verbs like estar and dar have regular imperatives in está and da.

You’ll be glad to learn that are no irregular vosotros imperatives, for however much help that is to you. :)

  • 1
    There is an irregular vosotros imperative: idos (by the rules, it should be íos), as well as iros which because of frecuency of use, the RAE has seen itself forced to accept as at least not incorrect. Also, interponer should be interpón. decir compounds (maldecir, bendecir) have regular tú commands: maldice and bendice instead of the expected maldí and bendí Jan 21, 2018 at 3:28
  • 1
    I think you have at least partially mistaken something. (yo-present) caber is quepo, which is consistent with my guess. Also I didn't include "vosotros imperative" (aka 2nd person plural imperative) in my question.
    – iBug
    Jan 21, 2018 at 3:52
  • 1
    @iBug Yes, indicative is yo quepo, but it’s also tú cabes; the subjunctive is therfore que tú quepas not que tú ✼cabas because of the irregular 1st-personal-singular stem. My vosotros quip was just a joke.
    – tchrist
    Jan 21, 2018 at 3:54
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    @iBug Yes, that’s right: you swap the -r for a -d. For the reflexive form though you don’t include the -d- except for idos. It’s sort of like how you drop the -s from 1st person plural reflexive imperatives: vámonos < vamos + nos.
    – tchrist
    Jan 21, 2018 at 4:04
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    @iBug I’m just trying to point out that the affirmative second-person commands are special; everything else uses present subjunctive.
    – tchrist
    Jan 21, 2018 at 16:20

I don't think there's a specific root for the present imperative. Though, the most closely related will be the one you mentioned, the conjugation of the present indicative but changing the last vowel to "a".

However, as every person studying Spanish know, there are not specific rules that fiil for anything. Here you can see an example of both, present indicative and subjective: http://www.rae.es/diccionario-panhispanico-de-dudas/apendices/modelos-de-conjugacion-verbal#n40

Hope that helps


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