Deloitte Access Economics expects Tasmanian retail turnover growth to outpace national growth in the current financial year, 2.5 per cent to 1.7 per cent.

It expects Tasmanian retail sales growth to tumble to 1.1 per cent in 2109-20 and 1.2 per cent in 2020-21, before a slight recovery.

The numbers were all much weaker than Tasmania's average annual sales growth of 3.8 per cent in the five years to 2017-18.

Deloitte said national retail sales weakened in 2018 and that was expected to continue into 2019 "as housing market pressures and lacklustre income growth hurt household budgets".

Recent Australian Bureau of Statistics figures for home loans and housing approvals showed the Tasmanian housing market was strongly outperforming the weakening national market (although rising house prices and rents can also hurt retail sales).

Deloitte economics partner and Retail Forecasts report principal author David Rumbens said: "Australia's retail sector has been sustaining a reasonable rate of sales growth in an unconventional way,  not so much from income growth, but leveraging off consumers' willingness to spend."

"That willingness to spend has been supported by very strong asset price growth, creating a massive windfall for one set of consumers.

"But for another and largely separate group, they have been associated with a significant lift in debt commitments.

"In recent years, both have run down their rate of savings from labour income, to support consumer spending at a faster pace of growth than it rightly should have achieved, given the economic fundamentals."

He said overall consumer spending growth in the past five years had averaged 2.5 per cent per year, but growth in household disposable income only averaged 1.9 per cent.

"That difference is a fair chunk of change, and it's fair to say that many retailers have only survived the last few years because we've lived beyond our means," he said.

"But that ship has now sailed."