Temporal conjunctions locate one event in time relative to another. Spanish has a rich family of them, and they share one tricky feature: after several of these conjunctions, the choice between indicative and subjunctive depends on whether you're talking about something real and habitual or about something that hasn't happened yet.
The core rule: indicative for real, subjunctive for pending
Compare these two sentences:
Cuando llegue a casa, cenaré.
When I get home, I'll have dinner.
The first describes a habitual reality — it happens every day — so it takes the indicative llego. The second refers to a future moment that hasn't happened yet, so it takes the subjunctive llegue. This alternation applies to almost every temporal conjunction in this list.
Cuando: when
Cuando is the workhorse of time expressions.
Llámame cuando puedas.
Call me when you can.
The first is past and habitual → indicative. The second is pending → subjunctive.
Mientras: while, as long as
Mientras sets two actions running in parallel.
Mientras cocinaba, escuchaba música.
While I was cooking, I was listening to music.
Mientras haya vida, hay esperanza.
As long as there is life, there is hope.
Again, the first describes a real simultaneous action; the second is a hypothetical condition about any future moment.
Hasta que: until
Hasta que marks the end point of an action.
Esperé hasta que llegó el tren.
I waited until the train arrived.
Voy a esperar hasta que llegue el tren.
I'm going to wait until the train arrives.
Antes de que and después de que
Antes de que (before) always takes the subjunctive, regardless of tense, because a before clause is always logically pending at the moment of the main action.
Llámame antes de que salgas.
Call me before you leave.
Después de que (after) technically follows the same real/pending rule as cuando, but in Latin America you'll hear the subjunctive used in a wide range of contexts — both are accepted.
Te aviso después de que hable con ella.
I'll let you know after I talk to her.
En cuanto and tan pronto como: as soon as
Both mean as soon as and follow the standard rule.
En cuanto supe la noticia, te llamé.
As soon as I found out the news, I called you.
Te aviso tan pronto como sepa algo.
I'll let you know as soon as I know something.
Desde que: since (point in time)
Desde que marks a starting point in the past and almost always takes the indicative, because you're anchoring a real moment.
Estoy feliz desde que me mudé aquí.
I've been happy since I moved here.
A summary table
| Conjunction | Meaning | Mood |
|---|---|---|
| cuando | when | indicative (real) / subjunctive (pending) |
| mientras | while, as long as | indicative / subjunctive |
| hasta que | until | indicative / subjunctive |
| antes de que | before | always subjunctive |
| después de que | after | indicative / subjunctive |
| en cuanto | as soon as | indicative / subjunctive |
| tan pronto como | as soon as | indicative / subjunctive |
| desde que | since | indicative |
Common mistakes
❌ Cuando llegaré a casa, te llamo.
Wrong: cuando + future is incorrect — use the subjunctive for pending events.
✅ Cuando llegue a casa, te llamo.
Correct: llegue (subjunctive) after cuando for future events.
❌ Antes que salgas, cierra la puerta.
Wrong: antes de que requires de — it is a three-word conjunction.
✅ Antes de que salgas, cierra la puerta.
Correct: antes de que + subjunctive.
❌ Mientras estudié, ella cocinaba.
Wrong: mientras describes simultaneous ongoing actions — use the imperfect.
✅ Mientras estudiaba, ella cocinaba.
Correct: both verbs in the imperfect for simultaneous actions.
For cause/reason structures, see Causal: Porque, Como, Ya que. For conditional structures, see Conditional: Si, A menos que.
Related Topics
- Causal: Porque, Como, Ya queA2 — How to express cause and reason in Spanish with porque, como, ya que, puesto que, and pues.
- Conditional: Si, A menos queB1 — How to build conditional clauses with si, a menos que, con tal de que, and other condition conjunctions.
- Concessive: Aunque, A pesar de queB2 — How to express although, even though, and even if with aunque, a pesar de que, and related conjunctions.