The preterit tense is one of the two simple past tenses in Spanish, and is used to talk about concrete, completed actions in the past. In this conjugation, -AR verbs have one set of endings and -ER and -IR verbs share a second set of endings.

Conjugation of regular -AR, -ER and -IR verbs in the preterit tense:

• Después de comer, yo lavé los platos y barrí el piso. (After eating, I washed the dishes and swept the floor.)
• Ella no lavó los platos ni barrió el piso. (She neither washed the dishes nor swept the floor.)

Note the accent marks on the first and third-person singular (“yo” and “él/ella/usted”) endings! These are important to distinguish the present and preterit tenses (Hablo = I speak; Habló = He/She/You spoke). Also note that the first-person plural “nosotros” endings are the same as the present tense for -AR and -IR verbs, and you’ll have to use the context to know which one is meant. There should be no confusion for -ER verbs since those endings are different:

• Nosotros siempre llamamos a mamá los domingos. (We always call Mom on Sundays. – present)
• Nosotros llamamos a mamá el domingo pasado. (We called Mom last Sunday. – preterit)
• Nosotros no sacudimos el polvo nunca. (We never dust. – present)
• Nosotros no sacudimos el polvo ayer. (We didn’t dust yesterday. – preterit)
• Nosotros barremos el patio. (We sweep the patio. – present)
• Nosotros barrimos el patio. (We swept the patio. – preterit)

Spelling changes in the preterit tense:

Some verbs require a spelling change in order to maintain consistent pronunciation of their consonants. These spelling changes follow consistent patterns, and in fact you have seen some of them before when you learned pluralization and some of the present tense verbs. In the preterit, these spelling changes are limited to the yo forms.

1. “Z” changes to “c” before “i” and before “e”. You should remember this from Spanish 1, when you learned pluralization (1 luz – 2 luces). In the preterit this happens in the yo forms of verbs whose infinitives end in -ZAR, for example:
   • Cruzar (to cross) – Yo crucé la calle. Tú cruzaste la calle. ¿Por qué cruzó la gallina la calle?
   • Empezar (to begin) – Yo empecé, tú empezaste, él empezó, ¡todos empezamos juntos!
2. Hard “g” to “gu”. This happens in the yo forms of verbs whose infinitives end in -GAR, for example:
   • Pagar (to pay) – Yo pagué mis impuestos. Tú pagaste tus impuestos. La compañía internacional, ¿pagó sus impuestos?
3. Hard “c” to “qu”. This happens in the yo form of verbs whose infinitives end in -CAR, for example:
   • Buscar (to look for) – Yo busqué un buzón de correos (mailbox). Tú buscaste un buzón. Buscamos un buzón para mandar una carta.
   • Sacar (to take out) – Yo saqué la basura ayer. Tú sacaste la basura anteayer. El no sacó la basura, es su turno hoy.
4. Intervocalic “i” to “í” and “y”. This happens in verbs that end in -EER and -UIR as well as “oír”, because the “i” in the endings either needs an accent mark so it doesn’t become a dipthong (first and second persons), or needs to change to a “y” to separate the strong vowels of the stem and ending (third persons). This change follows the rules of when words in Spanish need accent marks, but for now you could just memorize the forms.
   • Creer (to believe) – Yo lo creí (I believed it). Tú lo creíste. Ella lo creyó. Nosotros lo creímos. Vosotros lo creísteis. Ustedes lo creyeron.
   • Oír (to hear) – Yo lo oí (I heard it). Tú lo oíste. Usted lo oyó. Nosotras lo oímos. Vosotros lo oísteis. Ellas lo oyeron.

Spelling changes, from a different perspective:

Another way of looking at these spelling changes is to see them in the context of the Spanish alphabet: they’re not special irregularities peculiar to any particular tense, they’re just how Spanish spells particular sounds, regardless of when they turn up. If you look at them in terms of syllables, the pattern becomes clearer:

• (The soft “c”): ZA – CE – CI – ZO – ZU  In Latin American pronunciation this is indistinguishable from the “s” (SA – SE – SI – SO – SU). But the letter “z” is never used before the letters “e” or “i”, and switches to a “c” in those positions. So it’s understandable to confuse “sa” and “za” occasionally, but there’s no doubt about when to alternate “z” and “c”: alcanzar (to reach, achieve), alcancé, alcanzaste, alcanzó, etc.
• (The hard “c”): CA – QUE – QUI – CO – CU  Notice that the syllables “ce” and “ci” already are used for spelling the soft “c”, so the hard “c” needs to switch to the “qu” before “e” and “i”. Except for foreign words that use the letter “k”, there’s only one way to spell these syllable sounds in Spanish, no matter what the word is:  jaqueca (migraine), coquí (Puerto Rican tree frog), sacar, saqué, sacaste, sacó, etc.
• (The soft “g”): JA – GE/JE – GI/JI – JO – JU  This explains the spelling change that you remember from the present tense, with an -ER verb needing to preserve its soft “g” in front of the “o” of the yo ending: escoger, escojo, escoges, escoge, etc. But in the preterit, the endings for -GER verbs don’t stray into “j” territory: escoger, escogí, escogiste, escogió, etc.

• (The hard “g”): GA – GUE – GUI – GO – GU  Since the “ge” and “gi” are already taken for the soft “g”, the hard “g” adds a “u”. This is in a number of words that are probably familiar to you, for example guitarra and guerrilla. Why do -GAR verbs only change their spelling in the yo form of the preterit? Because the yo form is the only one with the vowel “e” (and no preterit endings of -AR verbs start with an “i”): entregar (to hand in), entregué, entregaste, entregó, entregamos, entregasteis, entregaron.