A lower birth rate and an ageing population means a diminishing tax base. How then is Australia going to support itself in the next few decades, if this continues?

The number of people aged between 15 and 64 for every older person has fallen from 7.3 in 1974-1975 to an estimated 4.5 this year. By 2054-55 that number is likely to be 2.7, according to Treasury statistics.

These figures presumably take into account current migration planning levels which have been set at 190,000 per year. But by the way things are going, it doesn’t look like it is enough.

Late last year, the ABS released statistics showing that the total birth-rate, or fertility rate, was 1.8 babies per woman. This rate is well below the replacement level of 2.1. Last year’s rate was lower than the 1.88 in 2013, and charts a downward trend evident for the past five years.

Altogether, 299,700 births were registered in Australia in 2014, down from 308,100 in 2013. For the first time the ABS mapped birth rates and found families in city centres have a much lower birth rates than outer suburbs, where the rate exceeds two children.

 “There was a strong pattern in our major cities where the highest birth-rates were in outer suburbs and very low rates in the inner city. These inner city areas had high proportions of younger people, but few babies,” ABS spokeswoman AJ Lanyon said.

Most babies are born to women aged between 30 and 34, although there has been a small increase in the birth-rate for 40 to 49-year-olds. Victoria has the lowest fertility rate and the Northern Territory the highest, at 2.1 births per woman.

A treasury report has noted that, “To maintain Australia’s existing age structure through immigration would require increases in immigration every year — and the increases would need to become progressively larger and larger to take account of the ageing of the migrants themselves.”

The Migration Council of Australia’s independent economic modelling last year indicated that Australia would need to raise migration levels to 250,000 per year in order to support the economy, maintain sustainable GDP levels and remain competitive internationally.