Old_Blighty

Hi all. First post on here, so apologies if this question has been done to death already. I am 51 years old, so a number of years yet before I hit retirement age. I have lived in Aus now for 25 years, but only paid NI for perhaps for 5/6 years back in the UK before emigrating to Aus. After building a portfolio of investment properties, I probably will not qualify now for an Aussie Aged Pension. However, I have been told that I can make voluntary contributions to my NI back in the UK, and still potentially qualify for a UK pension. As I did miss ‘many’ years of contributing, (and might not be eligible at all) - how much would I need to pay potentially to qualify for the UK pension? Knowing it’s not index linked, the diminishing spending power in time would become an issue too. I am 51 years old, so a number of years yet before I hit retirement age. Many thanks everyone in advance.