21 June

  • May monthly activity statements – final date for lodgment and payment.

30 June

  • End of financial year.

14 July

  • End of year finalisation declaration through STP due.
  • Payers must issue PAYG withholding payment summaries to payees (that is, employees and other workers) for payments not reported through STP.

21 July

  • Quarter 4 (April–June) PAYG instalment activity statement for head companies of consolidated groups – final date for lodgment and payment.
  • June monthly activity statements – final date for lodgment and payment.

28 July

  • Quarter 4 (April–June) activity statements – final date for lodgment and payment.
  • Due date for payment of super guarantee contributions for quarter 4 (1 April – 30 June) in the previous financial year – contributions to be made to the fund by this date.

If you do not pay minimum super contributions for quarter 4 by this date, you must pay the super guarantee charge and lodge a Superannuation guarantee charge statement – quarterly with us by 28 August. The super guarantee charge is not tax deductible.

Finalising all your PAYG instalments before you lodge your tax return will ensure you receive the correct amount of credit in your income tax assessment.

21 August

  • July monthly activity statements – final date for lodgment and payment.

28 August

  • Taxable payments annual report due for lodgment for some industries. 

SOURCE: ATO
This is a concise list of due dates. For a comprehensive list of dates, please visit the ATO website directly. 
https://www.ato.gov.au/Business/Reports-and-returns/Due-dates-for-lodging-and-paying/Due-dates-by-month