As per the information provided by the Australian Immigration department, Your husband can take IELTS or TOEFL or PTE examinations. How can I prove I have competent English? To prove that you have competent English you must provide evidence of one of the following: You hold a valid passport issued by the United Kingdom, the United States of America, Canada, New Zealand or the Republic of Ireland and you are a citizen of that country. You have achieved a score of at least 6 in each of the four test components (speaking, reading, listening and writing) in an International English Language Testing System (IELTS) test that has been undertaken in the three years immediately prior to lodging the visa application. You have achieved a score of at least 'B' in each of the four test components of an Occupational English Test (OET) that has been undertaken in the three years immediately prior to lodging the visa application. You have achieved the following minimum test scores in each of the four test components: 12 for listening, 13 for reading, 21 for writing and 18 for speaking, in a Test of English as a Foreign Language internet-based test (TOEFL iBT) test that has been undertaken in the three years immediately prior to lodging the visa application. You have achieved a test score of at least 50 in each of the four test components (speaking, reading, listening and writing) in a Pearson Test of English (PTE) Academic that has been undertaken in the three years immediately prior to lodging the visa application. You have achieved a test score of at least 169 in each of the four test components (speaking, reading, listening and writing) in a Cambridge English: Advanced (CAE) test that has been undertaken on or after 1 January 2015 and prior to lodging the visa application. read less

Hope you know that IELTS is a paper based test, while PTE is a computer based test. Though both these tests have similar sections of reading, listening, speaking and writing, the features of all these sections are not same in both. To understand the aspects better, go through the details of IELTS tasks and PTE tasks, identify which tasks are best suited to your strengths, and then decide which test will help you score better. read less