It's only deemed assessable income when payment is physically made.
If you are paid on the 30th of June, you'll get a group certificate for the pay your received.
If you are paid on the 15th of July, the income will be assessed in that year.
Interesting to note that some employers pay monthly - 2 weeks in arrears, 2 weeks in advance; if that arrangement was paid on the 30th June it's entirely assessable in that year even though you haven't done the work yet. That said, most employers that pay monthly paid mid-month rather than end of month.
Cheers
Buddybee