Future simple in complex sentences

The future simple tense is often used in the main clause of complex sentences that refer to future time and contain clauses of condition, time or purpose. In the subordinate clause (starting with if, when, as soon as, after, before, the moment etc.), we usually use a present tense:

If you have completed the course, you will receive a certificate. (condition)
As soon as I hear anything, I will let you know. (time)
I'm taking a book with me so that I'll have something to read on the train. (purpose)