The past conditional (or irrealis of the past) is used for hypothetical situations that did not happen, expressing alternative outcomes, missed opportunities, or regrets.
Forming the past conditional
Combine the past tense of zullen (zou or zouden) with a perfect auxiliary (hebben or zijn) and the past participle of the main verb.
In a standard main clause, zou(den) takes the second position. The perfect auxiliary and past participle go together at the end of the sentence.
| We would have informed you beforehand. | Wij zouden u vooraf hebben ingelicht. |
If the sentence begins with something other than the subject, invert the subject and zou(den) to keep the conjugated verb in the second position.
| In hindsight, I would have prevented the problem. | Achteraf zou ik het probleem hebben voorkomen. |
| Without you, we would not have prevented the accident. | Zonder jou zouden wij het ongeluk niet hebben voorkomen. |
Questions
To ask a question, invert the subject and zou(den).
| Would you have accepted this offer? | Zou jij dit aanbod hebben aangenomen? |
| Which alternative would you have considered? | Welk alternatief zouden jullie hebben overwogen? |
Using zijn instead of hebben
Just as in the present perfect tense, verbs indicating a change of state or motion (and exceptions like blijven) use zijn instead of hebben.
| Due to the storm, I would have stayed home. | Vanwege de storm zou ik thuis zijn gebleven. |