• lodge a tax return 
• ask about your personal tax affairs 
• apply for certain income assistance or support payments (such as pensions or benefits from either Centrelink or the Department of Veterans' Affairs) 
• make or receive payments under the Pay As You Go system 
• have savings accounts or investments that earn income - example: interest or dividends.

Self assessment
A self assessment system applies to all taxpayers which mean that taxpayers’ returns are not generally scrutinised by the ATO. The Taxation office relies on selective auditing of past returns and taxpayers’ affairs to monitor compliance with the tax laws. 

Spouses
Spouses are not taxed jointly. Each individual is treated as a separate taxpayer. 

Temporary status
If you are working temporarily in Australia for a period of six months or more, you are likely to be regarded as resident. Less than six months is likely to be regarded as a non resident. Note that these definitions apply to “residency for tax purposes”.

On a 4 year sponsorship visa you are considered a Temporary Resident (Long Stay). The difference to "permanent residency" is that you cannot vote, do not get full Medicare, and have to pay overseas student’s fees on any further education courses that you might want to take.

   

Tax Institute of Australia:
taxinstitute.com.au

The Board of Taxation: www.taxboard.gov.au

Business Entry Point www.business.gov.au

1. Complete your return as soon as possible, after you get your Group Certificate (The Group Certificate lists your earnings for the financial year). The sooner it is processed the sooner you will get your return. The return must be filed by October 30th for you to receive any rebate for the relevant tax year. 
   
   You can elect to have your rebate transferred electronically to your bank account. Australia Post operates an Express service for $21 which is worthwhile as it guarantees a return within 14 days. Envelopes are available from any Post Office.
   
2. Section 1 on Income is relatively straight forward, as all the details relating to your salary are included on your Group Certificate. The Group certificate must be lodged with your income tax return. PLEASE NOTE that you have to provide details of your Global Income which means declaring any income from overseas in terms of interest, profit from rental income, investments which generate an income dividend etc. These are all liable to tax in Australia for the period of your stay. 
   
   You should check whether you are liable to declare the other earnings in the other countries. If your income falls below the minimum for tax, you would simply add any additional income into your Australian return using the current exchange rate. If you are liable for any income in the other countries, you need to check whether it is better for you to be taxed in the other country rather than Australia. 
   
3. MEDICARE LEVY – for your first year you will not have to pay the levy for Medicare benefit unless your total income for that tax year is over $100,000. The levy only applies if you do not have any Private Medical Health Insurance and is equivalent to an additional 1.5% on your tax.
   
4. ADJUSTMENTS – if you have any dependent children then you are liable for Family Tax Assistance for the period between entering the country and the end of the tax year (June 30th). Similarly you can claim for a spouse over the same period which gives you a maximum additional allowance against tax of $1452.

In SUMMARY
The onus is on the individual to claim back what the government has taxed, rather than a system that tries to get it right and then amends via adjustments to a tax code the following year.

You can hire an accountant to do your tax return for you. Most will provide an initial consultation free and then you can decide whether you need them to complete the return or you feel confident to do it yourself – it depends on the level of complexity involved in your own personal tax situation.

   

Charging GST
Businesses are required to charge GST at the rate of 10% on goods and services that they supply to customers. The GST payable is included in the price paid by the recipient of the goods and services. The supplier must pass on this amount of GST to the Tax Office.

Getting credits for GST
If the recipient of goods or services is a business, it will normally be able to claim a credit for the amount of GST it has paid, provided it holds a tax invoice. This credit - called an input tax credit is offset against any GST which the business itself charges on goods and services it has supplied to its own customers.

Burden on end-consumer
The net effect is that businesses charge GST but do not keep it, and pay GST but get a credit for it. This means that they act essentially as collecting agents for the tax. The ultimate burden of the tax falls on the private consumer of the goods and services, as this person gets no credit for the GST he or she pays.

Registration
Most businesses will have to register for GST, although there are some exceptions. If a business is not registered, it normally cannot charge GST and cannot claim credits for the GST it pays.

Returns and tax periods
Businesses account to the Tax Office for the GST they charge and the credits they claim by making a GST return in their Business Activity Statement. A separate GST return is made for each tax period, which may be monthly or quarterly. Monthly returns are compulsory in some situations, such as where turnover is $20 million or more.

Accounting basis 
GST and credits are allocated to particular tax periods either on a cash basis (based on when amounts are received or paid out) or on an accruals basis (based on when invoices are sent or received). There are restrictions on who can use the cash basis.
Tax or refund? If the GST allocated to a tax period is more than the credits for that period, the business pays the balance to the Tax Office. If the credits exceed the GST, the business gets a refund. Adjustments may need to be made later if there is a change of circumstances.

GST exemptions 
Some transactions are outside the scope of GST altogether because, for example, they are gifts, or made by unregistrable people, or have no connection with Australia. Others are "GST-free" which means that the supplier does not charge GST, but can claim credits for the GST on its own acquisitions. The main GST-free items are exports, health, food, education, international travel and certain charitable activities.

Input taxed supplies
A small range of items are "input taxed". This means that the supplier does not charge GST and cannot claim credits for the GST on its own acquisitions. The main input taxed items are financial services and residential rent. 

Special rules apply to a wide range of items including imports, land development, insurance, motor vehicles, second-hand goods, charities and gambling.

Source: GST Solutions