Australia does have a tax year of July to June. I have the reverse problem, that all the US companies tax reports are not in keeping with when I have to report. I keep all my income payment records and WHT records and use them to report on my tax returns. Here any foreign paid tax is an offset for my local tax, so I dont get taxed twice.
The tax treaty between the USA and Australia means that income gets a 5% local tax not 30% local tax.