The average annual household electricity bill in Perth and the South West will rise by $134 from July 1 as a result of the Federal Government's carbon tax.
Financial modelling by electricity retailer Synergy reveals a household customer using an average 15.89 units of energy a day will pay an additional 9.13 per cent on their electricity bill.
The rise is in addition to the projected 3.5 per cent increase in electricity prices the State Government imposed in its Budget last month, which also applies from July 1.
Taken together, the average household's annual power bill will rise by $183, or $3.52 a week, to $1598.13.
Synergy's 9.13 per cent carbon tax increase is higher than that projected by WA's Economic Regulation Authority, which predicted a rise of 8.2 per cent. It is lower than Federal Treasury's 10 per cent prediction.
Federal Climate Change Minister Greg Combet said it meant the Gillard Government's household assistance package would "go further" for West Australians.
"The average WA household electricity bill will rise by around $2.50 a week - and the Federal Government is providing $10.10 a week on average to households in the form of tax cuts, higher family payments and increases in pensions and benefits," he said. "This gives the lie to the misleading claims by Tony Abbott that electricity prices would rise by as much as 30 per cent due to the carbon price."
Mr Abbott has promised to try to repeal the carbon tax if the coalition wins the next election.
Synergy is the only retailer of electricity to household customers in Perth and the South West.
Synergy chief Trevor James said it was announcing the rise now to give customers time to plan.
"Of course, the best way to keep electricity bills down is to use less energy and there are many opportunities to cut electricity use," he said.