it matters

1) used especially in questions and negative statements when you are talking about whether something is important

it matters that:

Why should it matter that he's a little overweight?

it matters if:

It doesn't really matter if we're a bit late.

Does it matter if I don't take a present?

2) used especially in questions and negative statements about whether something makes a difference

"I've forgotten my swimming stuff." "It doesn't matter – you can borrow these."

it matters that:

I don't think it matters that he hasn't got a degree.

it matters which/whether/how etc:

It doesn't matter how you look at it: the problem remains the same.