Australians earning low to middle incomes will be hardest hit by rising average tax rates over the coming decade, new analysis has found.

The Parliamentary Budget Office says the average tax rate will increase for Australians across all income brackets over the coming 10 years but the boost will be steepest for those in the low to middle group.

The rates will be going up largely because as wages rise, people will pay more tax on their increased income, the office has said in a report.