The formal commands (Ud. and Uds.) are based on the yo-form of the present indicative. First, take off the final -o. Then, add either -a or -an for verbs ending in -er and -ir, or -e or -en, for verbs ending in -ar. For example, note the following transformations from the infinitive, through the yo-form of the present indicative, to the Ud. and Uds. command forms:

Note that this holds for almost all verbs, including all those verbs that had an irregular stem in the present tense as well as stem-vowel changing verbs (e-to ie, e to i, and o to ue):

In some cases, Spanish spelling conventions cause a slight change in spelling. These are not true irregular forms because their pronunciation follows all the rules. But if one change the o to e after c or g, one must spell the resulting syllable que or gue in order to keep the sound soft. Likewise, zo changes to ce and (and vice-versa):

Finally, there are a few verbs whose Ud. and Uds. command forms do not follow these rules. In general, they are those verbs whose yo-forms in the present end in a y: doy, estoy, voy, soy, plus haber and saber:

That's it! To practice these forms, click on one of the following links:

Ud./Uds. Command Forms 1
Ud./Uds. Command Forms 2

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