ABN (Australian Business Number)

An ABN (Australian Business Number), is an 11 digit unique  identifier issued by the Australian Taxation Office that is used by  business entities when dealing with the Australian government. It was  introduced as part of the New Tax System brought in by John Howard’s  Liberal government on 1 July 2000 as part of the Goods and Services Tax.

Unlike with the TFN, the ATO has publicised the formula for checking and  creating valid ABN checksums. Also, the nature of the ABN algorithm  means that any 9 digit number can be made into a valid ABN.

Although applying for an ABN is not compulsory, if you are  required to register for GST you will need to have an ABN also.  Companies registered under the Corporations Law and businesses carrying  on business in Australia are entitled to an ABN. If your businesses  annual turnover is $75,000 or more a year, you must apply for an ABN and  register for GST. If your annual turnover is less than $75,000 per  year, you may choose to register an ABN at your own discretion.

Non-profit organisations with an annual turnover of $150,000 or  more, or if your business needs to be endorsed as a gift deductible  receipient or an income tax exempt charity you must also apply for an  ABN and register for GST.

Your ABN and GST registration are necessary for claiming GST  credits for goods and services you have paid GST on. For tax purposes,  you will need to quote your customers your ABN to avoid them withholding  tax at the top marginal rate.

It is a requirement that businesses registered for GST issue a  tax invoice quoting their ABN.