My husband is a tax consultant. This week he had a client who receives a pension alongside some casual work. The employer didn't consider the pension and withheld tax according to a lower tax bracket than she should have been in, considering both.

She owes nearly $5k. Hubby says "this employer is large and experienced, they absolutely should have known better". Poor woman.

Anyway, it's worth checking that your tax withheld from your paycheck is correct. If they aren't taking enough out, you'll have a balance to pay at tax time.