Spanish has one of the most expressive constructions in any Romance language: como si + imperfect subjunctive. It is how you say someone talks as if he knew everything, lives as if he were twenty, or acts as if nothing had happened. The construction takes a real, observable situation in the main clause and likens it to a counterfactual one in the subordinate clause — and the subjunctive is what tells the listener the comparison is hypothetical, not factual.
This page covers como si in all its everyday and literary uses, its less polite cousin ni que, the tense system that distinguishes simultaneity from anteriority, and the subtle pragmatic colouring that makes the construction so common in spoken Peninsular Spanish — especially in mild sarcasm, ironic admiration, and exasperated complaints.
The core rule: como si always takes the past subjunctive
This is the iron rule. After como si, Spanish allows only two tenses: the imperfect subjunctive (fuera / fuese, supiera / supiese) and the pluperfect subjunctive (hubiera sido / hubiese sido). It never takes the present subjunctive, never the present indicative, and never the conditional.
| Relation to main verb | Tense after como si | Example |
|---|---|---|
| simultaneous (same time as main clause) | imperfect subjunctive | Habla como si supiera de todo. |
| anterior (before main clause) | pluperfect subjunctive | Llegó como si hubiera corrido un maratón. |
The rule holds regardless of whether the main verb is present, past, future, conditional — the subordinate clause always picks past subjunctive forms.
Habla como si supiera de todo.
He talks as if he knew everything.
Hablaba como si supiera de todo.
He talked as if he knew everything.
Hablará como si supiera de todo.
He'll talk as if he knew everything.
The English equivalent shifts tense (talks / talked / will talk), but Spanish locks supiera in place. This is the single most common point of interference for English speakers — see Common Mistakes below.
Simultaneous comparison — imperfect subjunctive
When the comparison happens at the same moment as the main clause action, use the imperfect subjunctive.
Conduce como si fuera el dueño de la carretera.
He drives as if he owned the road.
Mi hermano vive como si tuviera veinte años, pero ya ha cumplido los cuarenta.
My brother lives as if he were twenty, but he's already turned forty.
Me miró como si no me conociera de nada.
She looked at me as if she didn't know me at all.
Está temblando como si tuviera frío, pero hace veinticinco grados en la calle.
He's shivering as if he were cold, but it's twenty-five degrees outside.
The -ra vs. -se choice
Both -ra and -se forms of the imperfect subjunctive are correct after como si. In Peninsular Spanish, the -ra form (fuera, supiera, tuviera) is overwhelmingly more common in speech and journalism. The -se form (fuese, supiese, tuviese) is preserved in literary prose, formal speech, and some regional dialects (notably parts of Galicia and the north).
Me trata como si fuera invisible.
She treats me as if I were invisible.
Me trata como si fuese invisible.
She treats me as if I were invisible. (literary or older speakers)
Both are perfectly grammatical. For everyday Spain Spanish, default to -ra.
Anterior comparison — pluperfect subjunctive
When the situation being compared happened before the main clause action, use the pluperfect subjunctive (hubiera / hubiese + participle).
Llegó al trabajo como si hubiera dormido en la calle.
He showed up to work as if he had slept on the street.
Me saludó como si no hubiera pasado nada entre nosotros.
She greeted me as if nothing had happened between us.
Está temblando como si hubiera visto un fantasma.
He's trembling as if he had seen a ghost.
Habla del proyecto como si lo hubiéramos terminado ayer mismo.
He talks about the project as if we'd just finished it yesterday.
The pluperfect signals that the fictional cause of the appearance happened earlier. The shaking is now; the imagined ghost-sighting was a moment ago. Without the perfect aspect, you would lose the cause-and-effect temporal sequence.
Imperfect vs. pluperfect — a clean contrast
The choice between the two tenses changes the meaning significantly.
Habla como si supiera la verdad.
He talks as if he knew the truth. (he gives the impression of being in the know now)
Habla como si hubiera sabido la verdad desde el principio.
He talks as if he had known the truth from the start. (he gives the impression that the knowledge was already his earlier)
Está cansado, como si trabajara mucho.
He's tired, as if he worked a lot. (ongoing situation)
Está cansado, como si hubiera trabajado toda la noche.
He's tired, as if he had worked all night. (completed prior event)
Ni que — the indignant cousin
Spanish has a parallel construction that English lacks a direct equivalent for: ni que + past subjunctive. It is used to reject the implied premise, usually with exasperation or sarcasm. The pattern is: someone behaves in a way that would only make sense if X, and the speaker objects to that X.
¡Ni que fuera de cristal! No me trates con tanto cuidado.
You'd think I were made of glass! Don't treat me so carefully.
¡Ni que tuviéramos dinero para tirar! Aquí cada euro cuenta.
You'd think we had money to burn! Around here every euro counts.
¡Ni que hubiera matado a alguien! Sólo he llegado diez minutos tarde.
You'd think I'd killed someone! I only got here ten minutes late.
¡Ni que fuera la primera vez! Ya hemos hablado mil veces de esto.
You'd think it were the first time! We've talked about this a thousand times already.
The flavour is almost always indignant: "Stop treating me like X — I'm not X!" Ni que is everyday Spanish in Spain, common in conversations among family and friends, in TV dialogue, and in opinion pieces with a sharp tongue. It is rarely used in formal writing.
Negation inside como si
Negating the como si clause is straightforward. The no goes immediately before the conjugated subjunctive.
Se comporta como si no le importara nada de lo que digo.
He behaves as if nothing I say mattered to him.
Sigue trabajando como si no hubiera pasado nada.
He keeps working as if nothing had happened.
Me miró como si no me hubiera oído.
He looked at me as if he hadn't heard me.
Como si in literary description
In literary Peninsular Spanish, como si is the workhorse of figurative description — it lets the writer compare an observable detail to an imagined cause, giving prose its evocative texture.
La casa crujía como si tuviera vida propia.
The house creaked as if it had a life of its own.
El silencio del salón pesaba como si guardara un secreto antiguo.
The silence of the room weighed like it was keeping an ancient secret.
La luz de la tarde se filtraba entre las cortinas como si dudara en entrar.
The late-afternoon light filtered through the curtains as if it hesitated to come in.
The trick in literary use is that the imagined cause does not need to be plausible — como si tells the reader to suspend disbelief and read the comparison as image, not claim.
Como si nada and other lexicalised expressions
A handful of como si phrases have become fixed expressions and behave as adverbs in their own right.
| Expression | Meaning | Example |
|---|---|---|
| como si nada | as if nothing were wrong / casually | Entró en la oficina como si nada y siguió a su mesa. |
| como si tal cosa | as if it were nothing | Se gastó dos mil euros como si tal cosa. |
| como si lloviera | without it bothering anyone | Se lo dije y como si lloviera, no me hizo ni caso. |
| como quien dice | so to speak | Vivimos en el mismo barrio, como quien dice, vecinos. |
Le presenté mi dimisión y se quedó como si nada.
I handed in my resignation and he didn't bat an eye.
Mi cuñado se compró un coche nuevo como si tal cosa, sin pedir consejo a nadie.
My brother-in-law bought a new car just like that, without asking anyone for advice.
Word order and stylistic variations
The default order is main clause + como si + subjunctive clause, but Spanish allows the subordinate clause to come first for emphasis. This is more common in writing than in speech.
Como si no tuviera bastantes problemas, ahora me llaman del banco.
As if I didn't have enough problems already, now the bank's calling me.
Como si lo hubiera ensayado toda la vida, recitó el discurso de un tirón.
As if he had rehearsed it his whole life, he delivered the speech in one go.
Fronting the como si clause sets up an expectation and then delivers the main event as the punchline. This is a favourite move in conversational complaints (como si no tuviera bastante con lo mío…) and in literary prose.
How this differs from English
English builds the same construction with as if or as though, but the tense system is muddier.
| English | Spanish |
|---|---|
| He talks as if he knew everything. | Habla como si supiera de todo. |
| He talks as if he knows everything. (colloquial) | (same Spanish — Habla como si supiera de todo.) |
| He looked at me as if he had seen a ghost. | Me miró como si hubiera visto un fantasma. |
| You'd think she was a movie star. | Ni que fuera una estrella de cine. |
Two mismatches matter most:
- English speakers under-mark the subjunctive. Colloquial English allows he talks as if he knows everything; Spanish does not allow habla como si sabe de todo. The subjunctive is non-negotiable.
- English has no ni que. The closest English equivalent is you'd think (that)… with mock-incredulous intonation. The Spanish exclamative ¡Ni que…! is sharper and lexicalised; it lives in conversation, not in writing.
Common Mistakes
❌ Habla como si sabe de todo.
Incorrect mood — como si never takes the present indicative; it requires the past subjunctive.
✅ Habla como si supiera de todo.
He talks as if he knew everything.
❌ Me trata como si fuese invisible, pero ahora me trata como si sea visible.
Tense locked — even when the main verb shifts to present or future, como si keeps the past subjunctive; you cannot switch to the present subjunctive.
✅ Me trata como si fuese invisible, aunque ahora me trata como si me viera por fin.
She treats me as if I were invisible, although now she treats me as if she finally saw me.
❌ Llegó como si corrió un maratón.
Tense error — the appearance is the result of a prior event, so the pluperfect subjunctive is required, not the preterite.
✅ Llegó como si hubiera corrido un maratón.
He arrived as if he had run a marathon.
❌ ¡Ni que sea el rey de España!
Mood error — ni que takes the past subjunctive, not the present subjunctive, even in exclamative use.
✅ ¡Ni que fuera el rey de España!
You'd think he were the King of Spain!
❌ Se comporta como si no me importaría su opinión.
Mood error — Spanish learners trained on conditional logic sometimes reach for the conditional after como si; it always takes the past subjunctive.
✅ Se comporta como si no me importara su opinión.
He acts as if his opinion didn't matter to me.
Key Takeaways
- Como si always takes the imperfect or pluperfect subjunctive — never the present, never the indicative, never the conditional.
- Imperfect subjunctive for simultaneous comparison (habla como si supiera); pluperfect subjunctive for anterior comparison (llegó como si hubiera corrido).
- The tense of the main verb does not affect the subordinate tense — Spanish locks past subjunctive after como si in all cases.
- Ni que
- past subjunctive is the indignant cousin: rejecting an implied premise with sarcasm or exasperation, common in spoken Spain Spanish.
- Both -ra and -se forms work after como si; in modern Peninsular Spanish, -ra is the default in speech and -se the literary alternative.
- The construction is a workhorse of literary description and conversational sarcasm; mastering it is one of the clearest markers of B2-and-beyond fluency.
Now practice Spanish
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Spanish→Related Topics
- Como si + imperfecto de subjuntivoB1 — Como si ('as if') always demands the imperfect or pluperfect subjunctive in modern Spanish — never the indicative, never the present subjunctive.
- -ra vs -se: dos formas, un valorB2 — How to choose between -ra and -se in peninsular Spanish — frequency data, register cues, and the one place the two forms genuinely diverge.
- Imperfecto de subjuntivo en oraciones con 'si'B1 — Build counterfactual present conditionals with si + imperfect subjunctive + conditional — and avoid the cardinal English-speaker error of putting the conditional or the indicative after si.
- Cadenas condicionales: si A entonces B y si B entonces CC1 — Multi-step conditional reasoning — chaining 'si' clauses across two, three or more steps — is where mood and tense coordination becomes a real puzzle. This page maps how to keep tenses aligned through long conditional chains.
- Deseos y arrepentimientos: si hubieraB2 — How to express wishes, regrets, and counterfactuals in Spanish — ojalá, si hubiera, tendría que haber, and the constellation of structures around them.