Business activity statement

The business activity statement (BAS) is a form submitted to the Australian Taxation Office (ATO) by registered business entities to report their tax obligations, including GST, pay as you go withholding (PAYGW), pay as you go instalments (PAYGI), fringe benefits tax (FBT), wine equalisation tax (WET) and luxury car tax (LCT). PAYGW is sometimes known as "Income Tax Withholding (ITW)," PAYGI is sometimes known as "Income Tax Instalments (ITI)".
The ATO forwards to each registered business before the end of each reporting period a BAS tailor-made for the business entity. The BAS may be delivered to the business as a paper form, electronically or via the business’s registered tax agent. Parts of the BAS may be pre-filled.
Related to the BAS is the Instalment Activity Statement (IAS), which is used by taxpayers who are not registered for the GST, but have other tax obligations. An IAS is also used by entities that prepare a quarterly BAS but are required to remit their PAYG withholding tax on a monthly basis.
The business activity statement reporting system was introduced in 2000 as a part of a major tax reform, which also included the introduction of the goods and services tax (GST). The various forms and reporting methods have changed considerably since the initial introduction of the BAS.
Types.
There are a number of different BAS forms which an organisation can complete. The form which a business receives depends on what tax liabilities it has, referred to as "roles". BASs are usually issued quarterly, some roles can be reported at different frequencies depending on the business structure and income. Some roles such as GST can be reported annually, subject to eligibility criteria being met.So BAS is a required statement.
Frequency.
Activity statements are usually required to be submitted quarterly, but some entities may be required to report obligations on a more frequent basis. 
Some entities may be required to report PAYG Withholding liabilities or GST on a monthly basis.
Operations.
Every activity statement carries a unique document identification number (DIN). Activity statements can be submitted to the ATO on paper (mail), by phone, electronically (via a Tax Agent's electronic lodgment system or "ELS"), or through the ATO business portal.
Activity statements are processed by the Australian Taxation Office through its operations sub-plan. Any errors which occur with activity statements are usually handled by a department known as activity statement product (exceptions {ASP(E)}). ASP(E) operates under the operations sub-plan, client account services (CAS) business service line (BSL). Errors may occur when a business client reports figures incorrectly, where a client includes cent figures (only dollar figures are allowable), where an arithmetic error occurs, when a statement is submitted when no roles are active for the client, or when the handwriting on a paper statement is illegible.
Methods of preparation.
The primary methods that businesses use to prepare and submit their business activity statement include: