BAS stands for “Business Activity Statement”. IAS stands for Instalment Activity Statement. An activity statement is a reporting document in which Australian business calculate and record all their tax liabilities for submission to the Australian Taxation Office (ATO).
The BAS and IAS were brought in with the introduction of GST in 2000 and is a regular, ongoing requirement for business once they become liable to pay business taxes. Whenever businesses file their BAS they have to pay any tax due, which allows the government to collect revenue sooner, and helps businesses to even out their cash flow by spreading out the payment of taxes over the year.