How to form the Present Subjunctive

Once you know how to form the Ud. command forms, you know almost everything there is to know about forming the present subjunctive. To make things a bit easier, the formation of the subjunctive has been divided into three categories below. In every case, the base form is the Ud. command form.

I. The yo, tú, Ud., él, ella, Uds., ellos, and ellas forms of the present subjunctive.

The Ud. command form is the same as that for the present subjunctive. In other words, tenga is both the Ud. command form and the Ud. present subjunctive form of tener. Of course, the él and ella forms are identical to the Ud. form, and, interestingly enough, so is the yo form. The Uds. form of the present subjunctive is just like the Uds. command form (or the Ud. command form with an n at the end). Not surprisingly, for the tú form, just add an s to the Ud. form:

yo                    tenga 
tú                    tengas 
Ud., él, ella         tenga 
Uds. ellos, ellas     tengan 

For most verbs, the nosotros and vosotros forms are just as easy: one adds mos and is to the to the Ud. form (remembering the accent on the vosotros form): tengamos and tengáis. Thus, for regular verbs, the entire paradigm is as follows:

yo              tenga      nosotros             tengamos
tú              tengas     vosotros             tengáis
Ud., él, ella   tenga      Uds., ellos, ellas   tengan

III. In addition to the regular forms above, there are (of course) some irregular verbs, but most of the irregularities are those already found in the Ud. command forms. In fact, the only additional irregularity occurs in the same stem-vowel changing ir verbs that have irregularities in other tenses. Just as was the case in the preterite and in the present participle, the o changes to u and the e changes to i, but only in the nosotros and vosotros forms. Here are two examples: pedir and dormir:

nosotros pidamos     nosotros durmamos
vosotros pidáis      vosotros durmáis

The rest of the forms are completely regular: yo pida, tú pidas, Ud., él, ella pida, and Uds., ellos, ellas pidan. Here is the complete paradigm for dormir:

yo              duerma      nosotros              durmamos
tú              duermas     vosotros              durmáis
Ud., él, ella   duerma      Uds., ellos, ellas    duerman

Notice, however, that in the rest of the stem-vowel changing verbs, the nosotros and vosotros forms have the same stems as in the present indicative (but that stem is different from the other forms):

yo              piense         nosotros            pensemos
tú              pienses        vosotros            penséis
Ud., él, ella   piense         Uds., ellos, ellas  piensen