New data shows average incomes are growing much faster in the wealthy inner-east and south than in less advantaged outer areas.

A Fairfax Media analysis of Australian Taxation Office figures found people in Melbourne's wealthiest suburb, Toorak, on average take home nearly five times as much as residents in the poorest, Springvale.

A little more than a decade ago, the difference was 3.5 times.

In Toorak, the mean income has leapt from leapt $95,416 to $173,808 over the past 11 years.

That equates to an 82 per cent increase to 2014-15.

In Springvale, the increase of 35 per cent over the same period is only slightly more than inflation. Mean income increased from $27,047 to $36,421.

The growing gap is broadly consistent across the city's 10 wealthiest and 10 poorest suburbs, measured by income.

With the exception of Portsea, the richest areas could be found in a band between Kew and Canterbury in the east down to Albert Park and Brighton on the bay. They recorded average income growth of between 63 and 94 per cent.

Incomes also rose in the poorest areas but, with the exception of Rosebud West on the Mornington Peninsula, at a slower rate.

Grouped in clusters in the south-east, north-west and west, these suburbs - including Broadmeadows, Doveton and Frankston North - had an average rise of between 35 and 51 per cent.

Grattan Institute chief executive John Daley said the data matched work by the think tank showing Melbourne was becoming more segregated between the "haves" in the city and the "have much less" further out.

The gap applies not just to income and income growth, but also education levels and female workforce participation rate.

"Yes, that segregation is going on, and yes, that's a problem," Mr Daley said.

He said there was also a growing gap in incomes within postcodes in Melbourne, particularly in the inner-city.

But he stressed the level of inequality in Australia was nowhere near as pronounced as in the US. Incomes in poorer suburbs in Australia grew by about 30 per cent over a decade. In America, wages have not increased for the bottom half in that time.

The gap between Melbourne's richest and poorest suburbs is growing fast. Photo: Paul Rovere

Monash University senior economics lecturer Gennadi Kazakevitch said the growing inequality was consistent with international trends, though the gap was generally less in Australia than elsewhere.

In terms of inequality and welfare safety nets, Dr Kazakevitch said Australia lay exactly in the middle between the US and northern Europe. He said a key question was whether living standards for those on lower incomes were increasing.

For no obvious reason, the largest and the smallest growth in incomes over the 11 years were recorded in nearby suburbs in Melbourne's outer north.

The residents of Yarrambat enjoyed an average 124 per cent jump in what they earned, from nearly $40,000 to almost $90,000.

But the people of Wollert, just 10 kilometres away, saw their incomes creep up only 2 per cent to $48,716.

The list of the 10 highest-earning Melbourne postcodes remains much the same as it did about a decade ago, but there has been one drop-out.

Postcode 3004, which takes in the section of the city that looks out on St Kilda Road, was ranked six for average taxable income back then, but it has been left behind by other affluent postcodes and now ranks at number 23.