Queenslanders are leading a spending boom as Australians open their wallets – or, more accurately, "flash their plastic" – on cars, holidays, hotels, motels and retail goods at the highest level in four years.

Queenslanders are now spending more at retail stores than at any time since June 2006.

Queensland shoppers are returning to department stores with the highest sales numbers since 2006. Credit:Fairfax

The Commonwealth Bank has since 2009 tracked the value of credit and debit card transactions every month processed at businesses with CommBank merchant facilities.

Spending has reached a four-year high, with Queenslanders spending more on their credit and debit cards than any other state.