Dummy "it"

“When is it a good time to call you?”

If I am correct that the “it” is an expletive or dummy “it” that is holding the place for the real subject, then what is the real subject in that sentence?

Thank you.

I think it’s a dummy “it”, but I wouldn’t say it was “holding the place for the real subject”. I think it’s more satisfying a grammatical requirement in a situation where there is no real subject.

A dummy subject is used when there is no real one, I suppose.

It snows in May.
There was only one man present there.

Thank you, Dozy and T.H., for your replies.


In “It is difficult to learn English,” “everybody” agrees that “it” is the dummy subject for “to learn English.” That is: To learn English + is + difficult.

Well, I was wondering about that “it” in my first post.

At another helpline, someone (quite confidently) opined that the “it” referred to “good time to call you.” So I was wondering what others thought, for I do not feel 100% comfortable with his suggestion.

Thank you.

I don’t agree with either of those theories. Substitution would give:

“To learn English is difficult to learn English.”
“When is a good time to call you a good time to call you?”

The first is nonsensical. The second is a strange question, like a riddle, which does not have the intended meaning.

Thank you, Dozy.