There is an exception to every rule, except the rule that states there's an exception to every rule. You can go crazy contemplating this paradox, but, as you study language, you become convinced that the statement is true. The good news about Spanish is that many of the exceptions to the rules are predictable. The most commonly used irregular verbs and the most important patterns to irregular verbs follow.
Common irregular verbs
Some verbs are so irregular that you will not be able to recognize when a conjugated form goes with the infinitive of the verb. The most irregular verbs in Spanish are also the most common, so you see the conjugated forms of these verbs often. Eventually, you will come to know the conjugated forms of these verbs so well that it may be difficult to remember the infinitive form. The verb ir means “to go .” Notice that the entire verb looks like the – ir infinitive ending, but it is conjugated nothing at all like a normal – ir verb. Also, notice that the conjugated forms of the verb ir in Table 1 look more like they come from some – ar verb with a v in it.
Once you get used to thinking that voy, vas, va, vamos, vais, and van all mean go or goes, it's hard to remember that the infinitive that means “to go” is the verb ir.
Another really irregular verb is ser, which means “to be .” Be aware that each word that follows a pronoun in Table 2 is the entire form of the verb.
As luck would have it, the most common form, es, sounds a lot like its English equivalent “is .”
Not only is ser irregular in its conjugated forms, it also has to compete with the verb estar, which also means “to be.”
Irregular verbs in the yo form
Several common verbs in Spanish are completely regular verbs except for the yo form. These are usually called yo irregulars. To help you remember the irregular yo form as you work through this section, verbs with the same irregular yo form are grouped together.
There are two extremely important verbs that are irregular only because the yo form of the verb ends in – oy: dar (to give) and estar (to be). As you can see in Tables 3 and 4, the rest of the forms of the verbs have regular endings.
Notice that the verb estar has accent marks on all forms except the first person yo and the first person plural nosotros/nosotras.
There are many verbs with a yo form that ends in – go even though there is not a single letter g in the infinitive. Most of these verbs are regular in all of the rest of their forms.
The four simplest and most common – go verbs are:
The verbs hacer, poner, and valer are all regular – er verbs with an irregular yo form that ends in – go. Tables 5, 6, and 7 show how to conjugate each verb.
Salir is a – go verb like poner, hacer, and valer. However, because it is an – ir verb, it will have the regular endings for an – ir verb, which differ slightly from – er verbs in the nosotros/nosotras and vosotros/vosotrasforms, as shown in Table 8.
The next two verbs, caer (to fall) and traer (to bring), follow the regular – er verb patterns of a – go verb, except for the irregular yo form, which adds an i to the conjugated form, as shown in Tables 9 and 10.
Three common – go verbs also fall under another irregular category called stem‐changing verbs. The irregular – go ending of the yo form follows to keep the list of ‐ go verbs together.
Normally you can't predict that a verb will be irregular in its yo form unless you already know the verb. There is one rule that is consistent, however. If the infinitive of the verb ends in a vowel followed by – cer or – cir, theyo form of the verb ends in – zco. Here are the infinitive forms of some of the most common –zco verbs:
These verbs are all conjugated exactly like conocer, which is the example used in Table 11. Use this table as model when you need to conjugate the other –zco verbs.
There are many verbs that end in – ducir. Because they all have the same ending, a vowel followed by – cir, they are conjugated the same way. All their forms are regular except the yo form, which ends in – zco.
Four common – ducir verbs are presented in the following list. The verb producir is conjugated in Table 12. Use that table as a model to conjugate the other three, as well as any other – ducir verb.
ver and saber
Two other verbs have unique yo forms. Both ver (to see) and saber (to know [a fact]) are regular – er verbs in all forms except the yo form, but their yo forms are completely different, as shown in Tables 13 and 14.