I should say in advance that my question is at least half answered here but not fully. (As I understand the answer here, 'it depends on if' is not good grammar. My question is if the same clause can work without the preposition.)
The question is whether the clause "it depends if" is correct or if it always needs to be "it depends [on] whether..."
I may have over-corrected the following (uncorrected) sentence in TEFL class today:
*It depends if my employers give me the day off.
My instinct was to correct to:
It depends on whether my employers give me the day off (or not)
In the meantime I have double checked with Micheal Swan Practical English Usage (11th ed.,p.456) which states:
If does not follow prepositions; we use whether instead.
But it also mentions that "[a]fter some very common words like tell, ask, depend, sure, idea, look, prepositions can be dropped before who, which, what and other question words".
This makes sense and I assume the following is correct.
It depends whether my employers give me the day off or not
But considering that the preposition has been dropped, I am now wondering if the "if" clause is also acceptable?
Are there clear rules here, or is it a matter of personal preference?