Subjunctive Triggers

Forming the subjunctive is one skill; knowing when it is required is another. The subjunctive lives in a subordinate clause, normally after 'que', and normally when the subject changes: 'Quiero que vengas'. But with the same subject you use an infinitive instead: 'Quiero venir'.

The classic trigger list is WEIRDO: Wishes (querer, esperar, preferir, ojalá), Emotions (alegrarse de, sentir, es una lástima), Impersonal expressions (es importante/necesario/posible/mejor), Recommendations and requests (pedir, sugerir, recomendar, aconsejar), Doubt and denial (dudar, no creer, no es verdad), Ojalá. The mirror image matters just as much: expressions of certainty take the INDICATIVE: creo que, es verdad que, es obvio que, sé que. Negate them and the subjunctive appears: 'Creo que viene' → 'No creo que venga'.

Six conjunctions always take the subjunctive because what follows is by definition unrealised: para que, antes de que, sin que, a menos que, con tal de que, en caso de que. Time conjunctions (cuando, en cuanto, hasta que, después de que, mientras, tan pronto como) take the subjunctive only when they point at the future: 'Cuando llego a casa, ceno' (habit, indicative) vs 'Cuando llegue a casa, cenaré' (future, subjunctive). Finally, an adjective clause takes the subjunctive when its antecedent is indefinite or non-existent: 'Busco un piso que tenga balcón' (any such flat) vs 'Vivo en el piso que tiene balcón' (a specific one).