Does "en cuanto" take the past subjunctive?
As soon as I found out you were leaving ...
2 Answers
Not always, when it refers to a moment of the future it does but when it refers to a moment habitual, present or past it takes the indicative tense. As soon as I get home I am going to take a hot bathe, en cuanto llegue: subjuntive When I arrived home I took a hot bath takes indicative.
Read this thread comparing en cuanto y tan pronto que to see examples of using the indicative mood and the present subjunctive after en cuanto.
So to answer your question, No.
If what follow the en cuanto refers to future time then the subjunctive mood will be used. (this includes future time in the past so the past subjunctive can be used, but it is not required in all cases)
En cuanto que tu padre llegue a casa, decidiremos tu castigo.