A small set of conditional conjunctions in Spanish — a menos que, con tal de que, sin que, en caso de que, siempre que (in its conditional sense), a no ser que — share one tidy feature: they always take the subjunctive. No matter the tense or the certainty level, the embedded verb is in subjunctive mood. This is one of the cleanest corners of the Spanish subjunctive system — the rule has no exceptions, no nuances, no dialect splits. You learn the list, you use the subjunctive, and you're done.
The big asterisk: this rule does not cover si ("if"), which is the most common conditional word in Spanish and has its own elaborate system. Si is treated separately on the conditionals guide page. This page covers the other conditional conjunctions.
Why these conjunctions all take subjunctive
A condition specifies a circumstance that would make something else true. The conditional clause does not assert that the circumstance is in fact the case — it just sketches what would have to hold. Spanish treats this lack of assertion as subjunctive territory, exactly as it does for purposes and wishes.
The intuition: when you say Te ayudo con tal de que me invites a un café, you are not asserting that I am buying you a coffee — you are sketching a contingent arrangement. The contingency is what the subjunctive marks.
The conditional conjunctions
| Conjunction | Translation | Notes |
|---|---|---|
| a menos que | unless | most common form for "unless" |
| a no ser que | unless | slightly more formal variant |
| salvo que | unless, except that | neutral, slightly formal |
| excepto que | unless, except that | neutral, slightly formal |
| con tal de que | provided that, as long as | condition under which something is acceptable |
| siempre que | provided that (conditional sense) | only subjunctive in conditional sense — see notes |
| siempre y cuando | as long as, provided that | more emphatic; common in writing |
| sin que | without (someone) doing | locks to subjunctive, no exceptions |
| en caso de que | in case, in the event that | preventive / contingency planning |
| como | if (conditional, threatening tone) | colloquial, see notes |
No iremos al concierto a menos que aparezcan las entradas.
We're not going to the concert unless the tickets turn up.
Te dejo el coche con tal de que lo devuelvas con el depósito lleno.
I'll lend you the car as long as you bring it back with a full tank.
Llévate el paraguas en caso de que se ponga a llover.
Take the umbrella in case it starts raining.
Salió de la habitación sin que nadie se diera cuenta.
She left the room without anyone noticing.
A menos que / a no ser que: "unless"
These two are interchangeable in meaning. A menos que is slightly more common in spoken Spanish; a no ser que sounds a touch more formal but is perfectly natural in conversation.
Both express a negative condition — the main clause holds unless the embedded clause becomes true. They are not optional alternatives to si no; they have their own syntactic life and lock to subjunctive.
No salgo de casa con este frío, a menos que sea estrictamente necesario.
I'm not leaving the house in this cold unless it's strictly necessary.
A no ser que te apetezca otra cosa, podemos pedir una pizza.
Unless you fancy something else, we can order a pizza.
No firmaré nada a menos que lo revise mi abogado.
I won't sign anything unless my lawyer reviews it.
A useful comparison: si no + indicative is the bare equivalent. No iré si no me invitas = No iré a menos que me invites. The a menos que version sounds slightly more elevated and emphatic.
Con tal de que / siempre que / siempre y cuando: "provided that"
This trio expresses a positive condition — the main clause holds as long as the embedded clause is met.
Con tal de que carries a slight whiff of "I don't care, just as long as…" — it can sound a touch resigned or transactional. Siempre que is more neutral. Siempre y cuando is the most emphatic and the most common in formal writing.
Te ayudo con la mudanza con tal de que me pagues con pizza.
I'll help you with the move as long as you pay me with pizza.
Puedes salir esta noche, siempre que vuelvas antes de las doce.
You can go out tonight, provided that you come back before twelve.
El plan funciona siempre y cuando todos cumplan con su parte.
The plan works as long as everyone does their part.
The trap with siempre que is that this conjunction has two distinct meanings, and only one of them is conditional:
- Siempre que
- subjunctive
- Siempre que
- indicative
The mood disambiguates them. Conditional sense → subjunctive; habitual temporal sense → indicative. This is parallel to the cuando / aunque pattern: same conjunction, mood does the semantic work.
Siempre que tengas tiempo, pásate por casa.
Whenever you have time / as long as you have time, drop by. (conditional → subjunctive)
Siempre que tiene tiempo, se pasa por casa.
Whenever he has time, he drops by. (habit → indicative)
Sin que: "without (someone) doing"
Sin que introduces an action that is not happening — the negation is built into the conjunction. It always takes subjunctive.
Entró en la habitación sin que lo vieran.
He came into the room without them seeing him.
No puedo concentrarme sin que haya silencio total.
I can't concentrate without total silence (without there being total silence).
The same-subject restriction applies: if both subjects are identical, drop que and use sin + infinitive.
| Different subjects → sin que + subjunctive | Same subject → sin + infinitive |
|---|---|
| Salió sin que sus padres lo notaran. (he left, parents noticed) | Salió sin decir nada. (he left, he said) |
| Compré el regalo sin que ella se enterara. (I bought, she found out) | Compré el regalo sin pensarlo dos veces. (I bought, I thought) |
Logré terminar el informe sin pedir ayuda a nadie.
I managed to finish the report without asking anyone for help. (same subject → infinitive)
En caso de que: "in case, in the event that"
En caso de que + subjunctive is contingency-planning language — what to do if something happens. It's the cousin of English "in case" or "in the event that".
Apúntate mi número en caso de que necesites algo.
Write down my number in case you need anything.
En caso de que llegues antes que yo, hay una llave debajo de la maceta.
In the event that you arrive before me, there's a key under the plant pot.
A near-synonym is por si (or por si acaso) + indicative — por si uses indicative, not subjunctive: Te dejo dinero por si necesitas algo ("I'm leaving you money in case you need anything"). This is one of the few conditional expressions that breaks the pattern, but it's a closed lexicalised expression rather than a productive conjunction.
Llevo dinero suelto por si pasa el revisor.
I'm carrying loose change in case the ticket inspector comes by.
Como + subjunctive: the threatening "if"
In conversational peninsular Spanish, como + subjunctive functions as a threatening or warning conditional. The construction is colloquial but extremely common — parents use it on children, partners use it on each other, friends use it as mock-threats.
Como llegues tarde otra vez, no te dejo entrar.
If you're late again, I'm not letting you in.
Como no apruebes este examen, te vas a llevar una buena bronca.
If you don't pass this exam, you're in for a real telling-off.
This is not the same as como meaning "since/because" (which takes indicative — Como llovía, nos quedamos en casa) or como meaning "like" (which is not conditional at all). Context and mood together identify the threatening reading. Reserve this construction for actually-threatening contexts; using it neutrally sounds aggressive.
The big exception: si
Of all conditional words in Spanish, only si ("if") does not follow this pattern. Si normally takes the indicative for open conditions in the present and future:
- Si vienes, te invito a cenar. (open / real condition) — indicative
- Si tienes hambre, hay pizza en la nevera. — indicative
For counterfactual conditions, si takes the imperfect or pluperfect subjunctive, not the present subjunctive:
- Si tuviera dinero, me compraría un coche. (counterfactual present) — imperfect subjunctive
- Si hubiera estudiado, habría aprobado. (counterfactual past) — pluperfect subjunctive
Si + present subjunctive is not a valid construction in modern Spanish. Never write Si vengas or Si tengas tiempo. The system for si is covered fully on the conditionals guide.
Same-subject restriction across the family
Several of these conjunctions allow a same-subject shortcut to infinitive:
| Conjunction | Same-subject infinitive form |
|---|---|
| sin que → sin + infinitive | Salí sin decir nada. |
| en caso de que → en caso de + infinitive | En caso de necesitar ayuda, llama. |
| antes de que → antes de + infinitive (see adverbial-time) | Me ducho antes de salir. |
| con tal de que → con tal de + infinitive | Soy capaz de cualquier cosa con tal de aprobar. |
| a menos que → no infinitive form available | — |
| siempre que → no infinitive form available | — |
The conjunctions that drop que for infinitive when subjects coincide pattern with para que (purpose) and antes de que (temporal). A menos que, salvo que, siempre que and siempre y cuando always keep their full form.
Common Mistakes
❌ No iré a menos que tengo tiempo.
Incorrect — a menos que ALWAYS takes subjunctive: tenga.
✅ No iré a menos que tenga tiempo.
I won't go unless I have time.
❌ Te ayudo con tal de que me pagas un café.
Incorrect — con tal de que takes subjunctive: pagues.
✅ Te ayudo con tal de que me pagues un café.
I'll help you as long as you buy me a coffee.
❌ Si vengas mañana, te invito a comer.
Incorrect — si never takes present subjunctive. Use indicative: vienes.
✅ Si vienes mañana, te invito a comer.
If you come tomorrow, I'll treat you to lunch.
❌ Salió de la fiesta sin que nadie lo vio.
Incorrect — sin que takes subjunctive: viera.
✅ Salió de la fiesta sin que nadie lo viera.
He left the party without anyone seeing him.
❌ En caso de que necesitas algo, llámame.
Incorrect — en caso de que takes subjunctive: necesites.
✅ En caso de que necesites algo, llámame.
In case you need anything, call me.
Key Takeaways
- A menos que, a no ser que, salvo que, excepto que ("unless") always take the subjunctive.
- Con tal de que, siempre que (conditional), siempre y cuando ("provided that") always take subjunctive.
- Sin que ("without") always takes subjunctive; same-subject → sin
- infinitive.
- En caso de que ("in case") takes subjunctive; the near-synonym por si takes indicative.
- Como
- subjunctive
- Si is the major exception — it does not take present subjunctive. Open conditions take indicative; counterfactuals take imperfect/pluperfect subjunctive.
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- Disparadores del subjuntivo: panoramaB1 — A master inventory of every grammatical trigger that forces the present subjunctive in peninsular Spanish — wishes, emotions, doubt, impersonal judgments, time, purpose, condition and more.
- Subjuntivo en cláusulas temporalesB1 — After cuando, mientras, en cuanto, tan pronto como and hasta que with future reference, Spanish uses the subjunctive — not the present or the future indicative. Antes de que always takes subjunctive; después de que is variable but strongly subjunctive in Spain.
- Subjuntivo de finalidad: para que, a fin de queB1 — Purpose conjunctions — para que, a fin de que, con el propósito de que, de modo que (intentional sense) — always take the subjunctive when subjects differ. With the same subject, Spanish switches to para + infinitive.
- Oraciones condicionales: guía completaB1 — A full reference for Spanish conditional sentences — the four classical types plus mixed conditionals, organised by how real the speaker considers the condition: factual, real-future, hypothetical, or counterfactual.
- Conjunciones condicionales: si, a menos queA2 — The three Spanish conditional patterns with si — real (si llueve, no voy), hypothetical (si lloviera, no iría) and counterfactual (si hubiera llovido, no habría ido). With the cardinal rule: never *si tendría.