Reckon you know which Illawarra residents earn the most? Guess again

The Australian Tax Office's recently released taxation statistics for the 2021/22 financial year show that Bulli - postcode 2516 - pipped the more prestigious postcodes directly to its north when it comes to income.

The 2516 postcode had the highest average taxable income in the region at $94,447.

Its northern neighbour, 2515, ranked second with an average income of $92,455, followed by the leafy, escarpment suburbs to the north (postcode 2508) with an annual average income trailing nearly $15,000 behind, at $78,086.

Most Illawarra postcodes recorded an average income of less than the national taxable income in 2021-22 (of $72,327), with Gerringong, Woonona, Figtree and Kiama the only others to top it.

But Regional Development Australia (RDA) Illawarra Shoalhaven board chair Mark McKenzie said the data, and especially the increase in incomes over five years, showed some interesting shifts across the region.

In Bulli, where the average income rose 30 per cent over five years, he said household wealth had been influenced by COVID-era migration out of Sydney.

"People were starting to take advantage of work from home, thinking about the fact that they don't need to worry about a daily commute," he said

"So we are seeing right across Australia's regions, a significant drift of people out of the urban fringe into the more affordable regional areas.

"What happens over time is that makes it less affordable - but with Bulli we've seen a drift of those who are quite mobile post-COVID and they can't necessarily get into the areas with traditionally very high wealth, so you're seeing that drift further south."

Mr McKenzie said the next five years would show if that northern suburbs wealth continues to migrate south into Woonona and Towradgi.

He said the latest figures also challenge the entrenched idea that the north of the Illawarra is rich and the south is poor.

"We're starting to see Shellharbour as a precinct really flex its muscle - its income climbed by 22 per cent in the last five years so it's now about average, and that's got to do with the significant development in that area," he said.

"We're seeing people get past that first home owner stage, to people consolidating their wealth."

He said the same thing was happening in the West Dapto development area, traditionally a low income postcode, where average taxable income climbed 24 per cent in five years.

"We're going to see a city the size of Wagga Wagga built in that area, and if we're attracting those sorts of households, it does significantly lift the purchase power of our region, which augurs well for business development," he said.

"But we are still seeing people left behind."

For instance the other end of the list, postcode 2502 (which includes Warrawong, Primbee and Cringila) had the lowest average annual income in the Illawarra, at $53,391.

This was followed by 2506 (Berkeley) at $56,149 and 2528 (Warilla, Barrack Heights, Windang, Mount Warrigal) at $59,295.

"These areas around Lake Illawarra are amongst the lowest in the country in terms of taxable income," Mr McKenzie said.

"So that identifies areas for us where we need to see greater investment in social infrastructure that boosts these households incomes, because we can't leave those groups behind."

The data also shows the spread of incomes in different suburbs, with more than 10 per cent of the population in Thirroul and Austinmer earning over $180,000 (that year's highest tax bracket) a year.

In Warrawong and Berkeley, fewer than two per cent of people who submitted a tax return earned this much.

Gerringong and Kiama, which rank among the highest earning suburbs when it comes to average annual income, had the highest proportion (about 20 per cent in both post codes) of people earning less than $18,200.