When does a conjunction call for the subjunctive?
Conjunctions join two actions. After some of them the subjunctive is always used, after others only when the second action has not happened yet. English gives no clue: before you leave, until I get back, so that you know all use a plain present tense.
Always subjuntivo
| Conjunction | Meaning |
|---|---|
| para que | so that |
| antes de que | before |
| sin que | without |
| a menos que | unless |
| en caso de que | in case |
Te lo digo para que lo sepas.
I am telling you so that you know.
Vete antes de que llegue mi madre.
Go before my mother arrives.
Lo hace sin que nadie lo sepa.
He does it without anyone knowing.
Iré a menos que llueva.
I will go unless it rains.
Llámame en caso de que necesites ayuda.
Call me in case you need help.
If the subject is the same in both parts, para, antes de and sin take the infinitive instead of que + subjuntivo, like English before leaving or without saying.
Llámame antes de salir.
Call me before you leave.
Salió sin decir nada.
He left without saying anything.
Depends on the time frame: cuando, hasta que, después de que
After cuando (when), hasta que (until) and después de que (after) the time frame decides. The same goes for en cuanto (as soon as). English refuses the future after when too (when you arrive, not when you will arrive), and Spanish refuses it in the same slot. Only the replacement differs: English uses the present, Spanish the subjunctive.
Future → subjuntivo
Cuando llegues, llámame.
When you arrive, call me.
Espera hasta que vuelva.
Wait until I come back.
Te llamaré después de que termine.
I will call you after I finish.
Past or habit → indicativo
Cuando llegué, ya no estaba.
When I arrived, he was already gone.
Cuando era niño, jugaba mucho.
When I was a child, I played a lot.
Esperé hasta que volvió.
I waited until he came back.
