NORTHERN Ireland families had £105 a week in discretionary income in the third quarter, according to the latest Asda Income Tracker.
It represents an 8.1 per cent rise on the same period of last year, although the pace of growth is slowing down.
And the spending power of households in the north remains well behind those in the UK as a whole, which have a £202 per week on average.
The slowdown in growth was attributed to an increase in essential item inflation such as clothing and housing costs, which rose 0.4 per cent in September - the largest increase since November 2014.
And with the value of sterling expected to remain weak, rising prices for imported goods will contribute to a higher rate of inflation over the coming months, Asda said.
An increase in restaurant and hotel prices, the cost of communications such as broadband and mobile bills, and alcohol and tobacco costs also contributed to the slowdown in spending power growth.
An Asda spokesman said: “As a retailer, it’s encouraging to see that UK families were able to benefit from a decline in food prices during September, especially as inflation and a weakened pound raised the cost of other essentials items."
Kay Neufeld, economist at Cebr which compiled the report added: “Household incomes continue to increase, but rising inflation is starting to take its toll on spending power. The weak pound means that price growth is going to accelerate further in the next months, increasing the cost of the weekly shopping."
