An auxiliary verb carries no real meaning on its own — it props up another verb to build a tense or a voice. Spanish has four major auxiliaries, and each one is locked to a specific construction: haber builds compound tenses, ser builds the passive, estar builds the progressive, and ir a builds the colloquial future. Knowing which auxiliary goes with which is half the battle of moving beyond simple sentences. This page shows you all four and warns you about the constructions you cannot mix.
The four auxiliaries at a glance
| Auxiliary | Construction | Built form | Example |
|---|---|---|---|
| haber | Compound tenses (perfect) | He comido. — "I have eaten." | |
| ser |
| Periphrastic passive | El puente fue construido en 1850. — "The bridge was built in 1850." |
| estar | Progressive | Estoy hablando con ella. — "I'm talking with her." | |
| ir a | Colloquial future | Voy a salir esta noche. — "I'm going to go out tonight." |
Two of these auxiliaries (haber and ser) take the past participle, which looks like an adjective. Two (estar and ir a) take a verbal form (the gerund — the -ndo form — and the infinitive respectively). Mixing them up is one of the most common errors learners make.
Haber: the compound-tense builder
Haber is the auxiliary for all compound (perfect) tenses in Spanish. It pairs with a past participle — hablado, comido, vivido, hecho, dicho, visto — to express that an action has happened by some reference point.
Its present-tense conjugation, which you will use constantly in Spain, is:
| Person | Form |
|---|---|
| yo | he |
| tú | has |
| él / ella / usted | ha |
| nosotros / nosotras | hemos |
| vosotros / vosotras | habéis |
| ellos / ellas / ustedes | han |
The vosotros form habéis is one of those identity-marking peninsular forms that you will hear in every Spanish café, classroom, and WhatsApp group chat. Latin American speakers say han instead.
¿Habéis comido ya, o esperáis a Marta?
Have you all eaten yet, or are you waiting for Marta?
He hablado con mi jefe esta mañana y me ha dado el día libre.
I spoke to my boss this morning and he gave me the day off.
No hemos terminado todavía el informe, lo siento.
We haven't finished the report yet, sorry.
Why haber is everywhere in Spain
Peninsular Spanish uses the pretérito perfecto (he comido) for hodiernal events — anything that happened today, this morning, this week, or that fits inside the time stretch the speaker still feels included in. In Latin America the same events would mostly be expressed with the simple preterite (comí). The result is that haber + participle is roughly twice as frequent in Spain as in most Latin American varieties.
Esta mañana me he duchado, he desayunado y me he ido al trabajo. Lo normal.
This morning I showered, had breakfast, and went to work. The usual.
Hoy he tenido tres reuniones seguidas y no he podido contestar tus mensajes.
Today I had three back-to-back meetings and couldn't reply to your messages.
A Latin American speaker telling the same story would more likely say Esta mañana me duché, desayuné y me fui al trabajo. Both are grammatical in both varieties, but the default changes across the Atlantic.
Haber in other compound tenses
The compound tenses had (pluperfect), will have (future perfect), and would have (conditional perfect) all use haber in the corresponding tense, plus the past participle:
| Tense | Yo + comer | English equivalent |
|---|---|---|
| Pretérito perfecto | he comido | I have eaten |
| Pluscuamperfecto | había comido | I had eaten |
| Futuro compuesto | habré comido | I will have eaten |
| Condicional compuesto | habría comido | I would have eaten |
| Pretérito perfecto de subjuntivo | haya comido | (that) I have eaten |
| Pluscuamperfecto de subjuntivo | hubiera/hubiese comido | (that) I had eaten |
The participle (comido) never changes — only haber moves through tenses and persons. This is one of the cleanest patterns in the language.
Cuando llegué a casa, mis padres ya habían cenado sin mí.
When I got home, my parents had already eaten dinner without me.
Para el lunes habremos terminado el proyecto, te lo prometo.
By Monday we'll have finished the project, I promise.
Impersonal hay — never agrees in number
A special use of haber in the third person singular is hay, the impersonal "there is / there are." Unlike English, Spanish does not make hay agree with the number of things being counted: you say hay un libro (one book) and hay tres libros (three books) with exactly the same verb form.
Hay un problema con la conexión a internet.
There's a problem with the internet connection.
Hay tres problemas que debemos solucionar antes del viernes.
There are three problems we need to fix before Friday.
The same applies in other tenses: había (there was/were), habrá (there will be), hubo (there was — for specific punctual events), ha habido (there has been). All invariable.
Ha habido un accidente en la M-30, hay caravana hasta la salida 17.
There's been an accident on the M-30, there's a traffic jam up to exit 17.
Ser: the passive-voice builder
When Spanish wants to express a true passive — focusing on the patient of an action rather than the agent — it uses ser + past participle. The participle agrees in gender and number with the subject (because here it really is functioning like an adjective).
El acueducto fue construido por los romanos en el siglo I.
The aqueduct was built by the Romans in the 1st century.
Las leyes son debatidas por el Congreso antes de ser aprobadas.
The laws are debated by Congress before being approved.
La novela ha sido traducida a más de veinte idiomas.
The novel has been translated into more than twenty languages.
The periphrastic passive is more characteristic of formal and journalistic Spanish; in everyday speech, peninsular speakers often prefer the impersonal se construction (Se construyó el acueducto en el siglo I) or simply switch to an active subject. The full mechanics live on verbs/passive-impersonal/passive-ser.
Estar: the progressive builder
Estar + gerund (the -ndo form) builds the Spanish progressive — used, like its English counterpart, to focus on an action in progress at a particular moment. The gerund is invariable.
Estoy escribiendo un correo larguísimo a mi tutor.
I'm writing an absurdly long email to my tutor.
¿Qué estáis haciendo? Llevamos media hora esperándoos.
What are you doing? We've been waiting for you for half an hour.
Estaba leyendo cuando sonó el teléfono.
I was reading when the phone rang.
Unlike English, Spanish does not use the progressive for the present-tense default. Hablo español covers both "I speak Spanish" and "I'm speaking Spanish (right now, generally)." The progressive estoy hablando is reserved for moments where the speaker wants to spotlight that the action is in flight at this specific instant. English learners over-use the progressive because it feels familiar; pull back unless the action is genuinely on screen right now.
Ir a + infinitive: the colloquial future
The other heavily-used periphrasis is ir + a + infinitive, the colloquial way to express future intentions and plans. It is the Spanish equivalent of English "going to" — and in conversational peninsular Spanish it is, by a long margin, more frequent than the simple future tense (hablaré).
| Person | Ir (present) |
|
|---|---|---|
| yo | voy | voy a salir |
| tú | vas | vas a salir |
| él / ella / usted | va | va a salir |
| nosotros / nosotras | vamos | vamos a salir |
| vosotros / vosotras | vais | vais a salir |
| ellos / ellas / ustedes | van | van a salir |
Este sábado vamos a quedar en casa de Pablo para ver el partido.
This Saturday we're going to meet up at Pablo's place to watch the match.
¿Vais a venir a la cena de cumpleaños o no?
Are you (all) going to come to the birthday dinner or not?
Te voy a contar lo que me pasó ayer en el supermercado.
I'm going to tell you what happened to me yesterday at the supermarket.
In Spain you will hear voy a llamarla roughly five times for every once you hear la llamaré. The simple future hasn't disappeared, but it has retreated to specific functions (predictions, conjectures, promises in formal contexts).
For the full mechanics — including ir a + infinitivo in the imperfect (iba a llamarla "I was going to call her") — see verbs/periphrastic/ir-a.
Auxiliary vs. lexical: when ser, estar, ir, haber are NOT auxiliaries
Each of these verbs also has a life as a full lexical verb, with its own meaning. Ser can mean "to be (essential identity, profession, origin)"; estar can mean "to be (location, state)"; ir can mean "to go (to a place)"; haber as full verb is mostly fossilized to the impersonal hay. When they take a past participle / gerund / infinitive partner, they are auxiliaries. When they take a noun or adjective complement, they are full verbs.
Voy al mercado. (lexical) — I'm going to the market.
*Ir* + a + place: lexical use, not the future periphrasis.
Voy a comprar leche. (auxiliary) — I'm going to buy milk.
*Ir* + a + infinitive: auxiliary use, the colloquial future.
Estoy en casa. (lexical) — I'm at home.
*Estar* + place: lexical use, locative *estar*.
Estoy comiendo. (auxiliary) — I'm eating.
*Estar* + gerund: auxiliary use, progressive aspect.
Periphrastic verbs that are NOT pure auxiliaries
Spanish has a wider family of verbal periphrases — tener que, deber, soler, acabar de, volver a, llevar + gerund — that look auxiliary-like but carry semantic weight beyond a simple grammatical function. Tener que expresses obligation, deber expresses ought, soler expresses habit, acabar de expresses "just-completed action," volver a expresses repetition, llevar + gerund expresses ongoing duration ("I've been working for hours"). These are covered in their own pages — they don't belong in the closed set of four pure auxiliaries above, because they all add meaning, not just structure.
Llevo dos horas esperándote, ¿dónde estás?
I've been waiting for you for two hours — where are you?
Acabo de hablar con tu madre y dice que llames.
I just spoke with your mum and she says to call her.
Common mistakes
❌ Estoy comido mucho hoy.
Incorrect — Spanish locks the perfect to haber, not estar.
✅ He comido mucho hoy.
Correct — compound perfect always uses *haber* + participle.
❌ Soy comido a las dos. (intended: I ate at 2)
Incorrect — *ser + participle* is the passive voice, not the perfect.
✅ Comí a las dos. / He comido a las dos.
Correct — use the preterite (or in Spain, the present perfect for today).
❌ Habían muchas personas en la fiesta.
Incorrect — impersonal *haber* is invariable, even with plural objects.
✅ Había muchas personas en la fiesta.
Correct — *había*, not *habían*, regardless of the number of people.
❌ Voy comprar pan. (missing *a*)
Incorrect — *ir + a + infinitive* requires the preposition *a*.
✅ Voy a comprar pan.
Correct — the *a* is obligatory.
❌ Estoy a comer. (meaning: I'm going to eat)
Incorrect — *estar + a + infinitive* is not a standard construction.
✅ Voy a comer. / Estoy comiendo.
Correct — *ir a* for intention; *estar + gerundio* for in-progress eating.
Key takeaways
- Haber is the auxiliary for all compound tenses; its present forms he, has, ha, hemos, habéis, han are everywhere in Spain because of the hodiernal use of the present perfect.
- Ser
- past participle builds the passive; the participle agrees with the subject.
- Estar
- gerund builds the progressive; do not over-use it where English would.
- Ir a
- infinitive is the workhorse colloquial future in Spain.
- Each of these verbs also has a full lexical meaning; the construction (what follows) tells you which job it is doing.
- Impersonal hay never agrees in number — and neither do había, hubo, ha habido.
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Start learning Spanish→Related Topics
- Haber como auxiliar de los tiempos compuestosA2 — How haber + past participle builds every compound tense in Spanish, and why the construction is far more frequent in peninsular Spanish than in Latin America.
- Pretérito perfecto: formaciónA2 — How Spanish builds the present perfect: haber in the present indicative plus the past participle, with the peninsular vosotros form habéis at the centre and the construction rules that govern pronoun placement and adverb position.
- Pasiva con ser: el libro fue escritoB1 — The full ser-passive: ser in any tense + past participle agreeing with the subject + optional por + agent. Register: formal, written, journalistic.
- Ir a + infinitivo: futuro y planesA1 — The workhorse near-future construction of spoken peninsular Spanish — voy a + infinitive for plans, intentions, and imminent events.