となると
Usage
「AとなるとB」 is used to express that "if A, the result or conclusion is B" when A has already come into existence "when it comes to; in such a case; if that happens"
Examples
いざ出発となると、不安になってきた
When it came time to leave, I became anxious
彼はとてもいいひとですが結婚となると、ちょっと頼りない気がする
He is a very nice person, but when it comes to marriage, he feels a little unreliable