[larac]

I need a few straight answers about tax but can't seem to find the information anywhere so I was hoping you guys could help.

First I've only been here for a few months;
- do I get taxed at 15% or 30%?
- do I get taxed only on what I have actually earned or my projected income for a whole year?
- do I have to contact the IRD or do they send me what I need to file a return unprompted?
- when do I have to pay tax?

Thanks