1
general::
Also, if or when it comes right down to. As regards, when the situation entails. For example, When it comes to renting or buying, you'll spend about the same amount. It is Also put as when it comes down to it or that, as in If it comes right down to it, they said you could visit any time you're able to, or When it comes to that, we can lend you the fare. This idiom uses come to in the sense of "amount to" or "be equivalent to." [Second half of 1700s]
American Heritage Idioms
2
general::
Phrase(s): when it comes to something
as for something; speaking about something. • When it comes to fishing, John is an expert. • When it comes to trouble, Mary really knows how to cause it.
McGrawhill's American Idioms And Phrasal Verbs