Same here in NZ - the main thing that makes it easy is that we have absolutely no deductions, if I have one employer my tax will likely be done perfectly. If I want I can go online with the IRD and fill out my tax form (my W2 equivalents are available), it's probably worth doing if I've had 2 jobs, if I don't the govt will do it for me and send me refund if I have one coming.

I run a small biz, I do PAYE on a simple spreadsheet, then type the results onto an IRD web page, takes me less than 10 minutes a month.