Time clauses: cuando, antes de que, hasta que

What it is

A time clause tells you when the main action happens. It starts with a connector such as cuando (when), antes de que (before), después de que (after), hasta que (until) or mientras (while). The real question is which mood its verb takes, and the answer depends on time:

• if the clause describes a fact, a habit or something that already happened, use the indicativo (indicative): Cuando llego a casa, me ducho.
• if it describes something that hasn't happened yet, use the presente de subjuntivo (present subjunctive): Cuando llegue a casa, te llamo.

English uses the present in both cases ("when I get home"), so in Spanish you have to make this choice every time. You already know the subjunctive forms; here they get one of their most frequent jobs.

How to form it

Connector + conjugated verb. The time clause can go first or second; when it goes first, add a comma.

When the time clause is about the future, the main verb can be a future, ir a + infinitive, an imperative, or simply the present with future meaning, which is the most common choice in conversation:

• Cuando termine, te aviso.When I finish, I'll let you know.present with future meaning
• Cuando termine, te voy a avisar.When I finish, I'm going to let you know.ir a + infinitive
• Cuando termines, avísame.When you finish, let me know.imperative

Antes de que is the exception: it always takes the subjunctive, even in a habit, because the action it introduces hasn't happened yet: Siempre salgo antes de que lleguen mis compañeros. In past stories it needs the imperfecto de subjuntivo (imperfect subjunctive), antes de que llegaran, which you'll learn at B2.

Same subject? Use the infinitive. When both actions have the same subject, antes de, después de and hasta take an infinitive instead of que + subjunctive:

Finally, al + infinitive means "when" or "on doing": Al llegar, vi el mensaje.

When to use it

Future events → subjunctive. As soon as the time clause points to the future, its verb goes into the present subjunctive, whatever the main clause does:

• Cuando termine la carrera, quiero viajar por Latinoamérica.When I finish my degree, I want to travel around Latin America.a plan
• Cuando llegues a Lima, mándame un mensaje.When you get to Lima, send me a message.an instruction
• Te espero aquí hasta que salgas del consultorio.I'll wait for you here until you come out of the doctor's surgery.until a future moment
• Quiero hablar con mi jefa antes de que se vaya de vacaciones.I want to talk to my boss before she goes on holiday.antes de que: always subjunctive

Habits and the past → indicative. If something happens regularly or already happened, it's a fact: Cuando tengo una entrevista, siempre llego diez minutos antes. Cuando Diego se mudó a Santiago, no conocía a nadie. The same goes for hasta que: Trabajé en esa tienda hasta que cerró.

Questions → indicative. ¿Cuándo? in a question never takes the subjunctive: ¿Cuándo vienes a Guatemala? The subjunctive turns up in the answer: Cuando tenga vacaciones.

Mientras (while) links two actions happening at the same time and normally takes the indicative: Mientras tú cocinas, yo pongo la mesa.

Al + infinitive is a compact "when" or "as", usually with the same subject, and common in writing: Al salir de la oficina, vi que estaba lloviendo.

Contrasts and traps

• No future after cuando. Say cuando llegues, never cuando llegarás. The future belongs in the main clause: Cuando llegues, cenaremos.
• Habit or one future occasion? Cuando llego a casa, me ducho is what you do every day; Cuando llegue a casa, me ducho is about tonight.
• Same subject → infinitive. Antes de salir, apago las luces, not antes de que salga.
• Si is not cuando. Real conditions take the indicative: Si puedes, llámame, but Cuando puedas, llámame.
• Mexican hasta. In Mexico and Central America, hasta can mark when something starts: Abren hasta las diez means "they don't open until ten". You only need to recognise it.
• Coming at B2. En cuanto and tan pronto como (as soon as) follow the same rule: En cuanto sepa algo, te aviso.

If you also speak Portuguese

Portuguese uses its future subjunctive here (quando eu chegar, quando você puder), which looks just like an infinitive and leads to cuando llegar. Spanish uses the present subjunctive instead: cuando llegue, cuando puedas. A personal infinitive (antes de você sair, até você voltar) becomes que + subjunctive: antes de que salgas, hasta que vuelvas. And while Portuguese says se você puder, Spanish si takes the indicative: si puedes.