Dutch conditionals express hypothetical situations. The real conditional (something that may actually happen) uses the present tense in both clauses: “Als het regent, neem ik een paraplu” (If it rains, I take an umbrella). The unreal conditional (hypothetical or contrary to fact) uses the imperfect in the if-clause and zou(den) + infinitive in the main clause: “Als ik rijk was, zou ik een groot huis kopen” (If I were rich, I would buy a big house).
The past unreal conditional describes something that did not happen in the past: “Als ik eerder was gekomen, had ik jou gezien” (If I had come earlier, I would have seen you). This construction uses als + pluperfect + had(den)/zou(den) hebben/zijn + past participle. It appears in literary Dutch and formal writing and is worth recognizing even if you rarely produce it at first.
Word order note: when the als-clause comes first, the main clause triggers V2 inversion — the verb comes before the subject: “Als het regent, neem ik een paraplu” → neem ik (verb before subject). This is a good V2 drill opportunity. Als means both “if” and “when” in Dutch — context distinguishes them. For “if” in the subjunctive sense, indien is the formal alternative, and wanneer means “when” in time-reference contexts.