IELTS is accepted for many visa categories, as well as for permanent residency in Australia. It is also a requirement for some Australian professional organisations and accrediting bodies.
If you are applying for a work visa, professional recognition or for permanent residency in Canada, it is likely that you will be required to present evidence of English language proficiency. IELTS General Training is the only internationally available English proficiency test accepted by Immigration, Refugees and Citizenship Canada (IRCC) for immigration to Canada.
The New Zealand government asks for IELTS as evidence of English language proficiency for many visas, including those within the Skilled Migrant, Investor and Entrepreneur, Residence from Work and Parent categories.
Evidence of English language ability is a requirement for those applying to settle permanently in the UK (also known as applying for 'leave to remain' or 'long residence').