Conjugation of ser

Ser means “to be” when Catalan identifies, classifies, defines, dates, or locates an event. It is one of the language's most frequent and most irregular verbs. English learners cannot obtain soc, era, fou, and sigui from one visible stem; the useful strategy is to learn those forms as a small set of principal parts and let each principal part predict a whole tense.

This is a conjugation reference. For the choice between the two copulas, see ser versus estar. The broad general standard forms below suit both ordinary conversation and (formal) writing; explicitly labeled forms belong to another register or regional standard.

Nonfinite forms and principal parts

Both ser and ésser are standard. Ser is the usual unmarked citation form; ésser is especially visible (formal) and (literary). The gerunds sent and essent are both standard; colloquial siguent is not the general formal form. As the participle in a compound tense, estat stays invariable: elles han estat amables. In a passive such as una porta que havia estat oberta, the agreeing word is the lexical participle oberta; auxiliary estat remains invariable.

Sigut is also a standard participle and is especially familiar in western and Valencian usage (regional: Valencian / Northwestern). The general reference tables use estat, which is accepted throughout the domain.

Indicative: simple and periphrastic tenses

The present is suppletive: it mixes forms inherited from different historical bases. Do not regularize it as sero or add the third-conjugation incoative extension -eix-; forms such as sereixo do not exist. Modern spelling has soc without the former diacritical accent. By contrast, és and són retain accents: és differs from the weak pronoun es, and són differs from the possessive/noun son.

The imperfect era presents identity or description from inside an ongoing past situation. The periphrastic past presents the situation as a bounded whole and is the everyday past throughout the language. The synthetic simple past is productive but chiefly (formal/literary) in much Central usage; it remains alive in some Valencian and Balearic communities (regional). Unlike Spanish, Catalan does not share this past paradigm with anar: fou director means “he was director,” never “he went.”

Future and conditional forms return to the transparent stem ser-. Besides future time, serà can express a reasoned guess: Serà la veïna means “It must be the neighbor.” The conditional is frequent in polite evaluations such as seria millor and counterfactual conclusions.

The alternative conditional series fora, fores, fora, fórem, fóreu, foren is also standard. It is particularly established (regional: Valencian) and appears in elevated writing (formal/literary); the unambiguous general learner model is seria, series.... Do not confuse conditional fora “would be” with imperfect-subjunctive fos “were.”

Indicative: compound tenses

Every compound tense uses a finite form of haver plus the invariable participle estat. Nothing is inserted between the auxiliary and participle; weak pronouns precede the whole verb group.

The past anterior is now mostly (formal/literary) and normally follows a temporal connector: tan bon punt hagué estat nomenada.... A periphrastic past anterior (vaig haver estat, vas haver estat, va haver estat, vam haver estat, vau haver estat, van haver estat) is grammatical but uncommon because discourse rarely needs to mark “had been” as an immediately completed bounded event.

Subjunctive and its compound forms

The sigu- and fo(s)- families are both irregular and must be learned. The present subjunctive places the relation inside a wish, evaluation, doubt, purpose, or other nonasserted frame; the imperfect relates that frame to a past viewpoint or an unreal condition. English often leaves the verb “be” unchanged, so the Catalan mood contrast is easy to miss.

Three further periphrastic rows complete the reference system. They have restricted distribution (regional/formal); ordinary general-standard speech normally chooses a perfect or imperfect form from the tables above.

Imperative and weak pronouns

There is no first-person-singular imperative. In an affirmative command, an attached pronoun follows the verb (sigueu-hi); in a negative command it precedes it (no hi sigueu). Catalan ser is not freely pronominal: sequences such as ser-hi “be present/there” and ser-ho “be so/be it” contain ordinary weak pronouns, not a dictionary verb ser-se.

Core uses, government, and regional standards

Use ser for identity and classification (és metgessa), origin or material (és d'Alcoi; és de fusta), time (són les sis), and event location (el concert és al teatre). With people and things, the traditional Central baseline also uses ser for neutral location: la clau és al calaix. Estar foregrounds a state, resultant position, duration, residence, or continued presence. The old “permanent versus temporary” slogan fails because identity can change and a resultant state can last forever.

Government matters. Origin and material take de: ser de Girona, ser de vidre. Neutral location normally takes a before a definite place: ser a l'oficina. Do not copy English “be in” mechanically, and do not use a before a profession after the copula.

In (regional: Balearic) speech, first-person singular som is usual alongside first-person plural som. (Regional: Valencian) has present eres beside ets, present subjunctive siga, sigues, siga, siguem, sigueu, siguen, and imperfect-subjunctive fora forms alongside the general fos series. The participle sigut is particularly frequent in Valencian. These are coherent standard regional paradigms, not errors. The older present-subjunctive series sia, sies... is now chiefly (archaic/literary) or fossilized in sia com sia.

Common Mistakes

Key Takeaways

The paradigm is best remembered as families: soc for the suppletive present, era for the imperfect, fou for the (formal/literary) simple past, ser- for future and conditional, sigui for present subjunctive, fos for imperfect subjunctive, and estat for compounds. In everyday past narration, choose vaig ser rather than fui. Keep és/es and són/son distinct in writing, and treat ser-hi or ser-ho as ser plus a weak pronoun—not as new pronominal infinitives.