The annual rate of inflation is expected to have fallen sharply in official figures to be released today, because of the repeal of the carbon tax.

The annual rate of inflation currently sits at 3 per cent, right at the top of the Reserve Bank's comfort zone.

Economists surveyed by Bloomberg are typically forecasting the rate will fall to 2.3 per cent when the September quarter's figures are released today.

That reflects their expectations of a 0.4 per cent rise in prices during the quarter, though NAB senior economist Spiros Papadopoulos predicts that prices were stagnant in the period.

He said the scrapping of the carbon tax is the key, with some unusual outcomes expected, including the first quarterly decline in electricity prices since 1999.

"We saw when the carbon tax was introduced a couple of years ago that we had a big increase in the September quarter of 2012 and obviously now, with the removal of the carbon tax, we're going to see the first evidence of that in the CPI figures today, and in the next couple of quarters there's also likely to be some impact," he explained.

However, Mr Papadopoulos added that, as it did with price rises resulting from carbon pricing, the Reserve Bank will look past any price falls associated with its removal.

"They don't want to be conducting policy just on the back of a change in government legislation, so they'll look at the underlying rate, which will mostly exclude the impact of the carbon tax removal," he said.

He also expects lower fuel prices in the quarter.