Hypothetical conditions: si + imperfect subjunctive

What it is

Spanish has two main kinds of if-sentences. Real conditions talk about things that may well happen: Si tengo tiempo, te llamo (you met these at B1). Hypothetical conditions imagine something that is not true now, or that you think is unlikely to happen: Si tuviera tiempo, te llamaría, "If I had time, I'd call you" (but I don't, so I won't). Grammars call this the condicional irreal de presente: the si clause takes the imperfect subjunctive and the result clause takes the conditional. Despite the past look of tuviera, the sentence is about now or the future, exactly like English if I had.

How to form it

Two clauses, two moods. The si half uses the imperfect subjunctive from the previous topic (tuviera, fuera, pudiera, supiera); the result half uses the conditional (tendría, sería, podría, haría).

The order is free. When the si clause comes first, put a comma after it; when it comes second, leave the comma out: Viajaría más si tuviera más dinero. Review the irregular conditional stems, which are the same as in the future: tendría, pondría, saldría, vendría, podría, sabría, querría, habría, haría, diría. The -se form is also correct in the si clause (Si tuviese más dinero…), but it sounds more formal; in Latin American speech, use -ra.

When to use it

• Imagining a different present: Si viviéramos en la costa, iríamos a la playa todos los fines de semana. (We don't live there.)
• Unlikely futures: ¿Qué harías si te tocara la lotería? You could win, but you don't expect to.
• Advice: Si yo fuera tú, hablaría con ella cuanto antes. The shorter Yo en tu lugar… works the same way: Yo en tu lugar, no firmaría ese contrato todavía.
• Hypothetical questions, the kind that start conversations or come up in job interviews: Si fueras presidenta, ¿qué cambiarías primero?
• Offers with a catch: Te prestaría mi carro si no lo necesitara mañana.

• Si tuviera más tiempo, aprendería a tocar el piano.If I had more time, I'd learn to play the piano.an unreal present
• ¿Qué harías si te tocara la lotería?What would you do if you won the lottery?an unlikely future
• Si yo fuera tú, hablaría con ella cuanto antes.If I were you, I'd talk to her as soon as possible.advice
• Te prestaría mi carro si no lo necesitara mañana.I'd lend you my car if I didn't need it tomorrow.result first, no comma

Contrasts and traps

• Real or hypothetical? You decide. Si tengo tiempo, voy (quite possible) and Si tuviera tiempo, iría (I doubt it) are both correct; they say different things about likelihood. Don't mix the halves: ✗ Si tuviera tiempo, voy, ✗ Si tengo tiempo, iría.
• Never the conditional after si. ✗ Si tendría dinero is the classic mistake for learners of every language. You may hear it in some regions, but it is non-standard. The conditional belongs in the other clause: Si tuviera dinero, compraría una casa.
• Never the present subjunctive after si. ✗ Si tenga tiempo is wrong. After si (if), use the present indicative for real conditions or the imperfect subjunctive for hypothetical ones.
• Not the imperfect indicative either. English and French speakers sometimes write ✗ Si tenía tiempo, iría, because had and avais look like past tenses. Spanish needs the subjunctive: tuviera.
• No -ra in the result clause. ✗ Si tuviera dinero, comprara una casa is regional or old-fashioned. Standard Spanish uses the conditional: compraría.
• si ≠ sí. Without an accent, si means "if"; with one, sí means "yes".

If you speak Portuguese

The structure maps almost one to one: Se eu tivesse dinheiro, viajaria → Si tuviera dinero, viajaría. Watch the spelling (si, not se; -ra, or -se with a single s), use the conditional in the result clause even where Brazilian speech says eu viajava, and don't let the Portuguese future subjunctive (se você tiver) push you into si tuvieras for real conditions: that is si tienes.