The latest figures from the Central Statistics Office show that consumer prices posted an annual fall of 1% in December.
The CSO said this compared to a fall of 1.5% in October, when consumer prices saw their sharpest fall for a decade.
Consumer prices have now dropped on an annual basis for nine months in a row since Covid-19 restrictions were first introduced in March.
On a monthly basis, prices were 0.3% higher in December, unchanged from November, the CSO figures showed.
Today's figures show that transport costs fell by 4.1% on an annual basis in December due to lower prices for diesel and petrol and a reduction in air fares, with these reductions partially offset by higher prices for cars.
Clothing and footwear costs were down 7.8% fell due to sales.
December also saw lower prices for home heating oil, lower rents and a fall in the cost of natural gas. But these reductions were partially offset by an increase in the cost of electricity and higher mortgage interest repayments.
Health costs also rose mainly due to an increase in the cost of medical and dental services in December, the CSO said.