The fall can be principally attributed to stability in average gas and electricity bills, which were unchanged between August and September this year but rose a year ago.
Late summer 2008 was around the time some of the major energy suppliers chose to increase their tariffs.
Other downward pressures on CPI inflation came from food and non-alcoholic beverages, restaurants, hotels, recreation and culture.
Earlier this week, the Irish Times reported that switching gas and electricity supplier can save money as the recession ensues.
The newspaper claimed that households can save up to ten per cent on their annual bills by choosing the most attractive tariffs available on the market today.
It said the process of switching energy provider is "genuinely easy", urging consumers to take this step to reduce their household expenditure.
Click here to run an energy price comparison, and see if you could be paying less for your gas and electricity.