The annual cost of living increase, as measured by StatsNZ's Household Living-costs Price Indexes (HLPI), is the highest recorded since the series began in 2008 for seven out of the 13 household groups. 

The increase in living cost was higher for every household group in the December 2021 quarter compared with the December 2020 quarter, with living cost increases ranging from 4.8 per cent for the beneficiary household group to 5.4 for the highest-spending household group. 

Each quarter, the HLPI measures how inflation affects 13 different household groups, while the consumer price index (CPI) measures how inflation affects New Zealand as a whole. 

By looking at spending patterns of the different demographics and comparing them with which products and services are seeing the biggest price rises the HLPI provides insight into where the real pain of inflation is falling. 

While inflation measured by the CPI was 5.9 per cent from December 2020 to the December 2021 quarter (see Consumers price index: December 2021 quarter), inflation for the average household as measured in the HLPIs was 5.2 per cent. 

In the past, the HLFI has shown those on fixed incomes - like beneficiaries and superannuants - suffering the worst effects of inflation. 

But the latest data shows high-spending households experiencing the greatest rise in living costs - at 5.4 per cent. 

This was mainly influenced by higher prices for petrol, mortgage interest payments, and second-hand motor cars, StatsNZ said. 

Prices for all interest payments, including mortgage interest payments, increased 7.8 per cent in the December 2021 quarter. 

"Highest-spending households spend 7.3 per cent of their expenditure on interest payments, compared with 4.6 per cent for the average household," StatsNZ said. 

"This means the highest-spending households experience the price increase more than others." 

Māori households experienced an annual living-cost increase of 5.3 per cent from December 2020 to the December 2021 quarter, compared with the 5.2 per cent experienced by the average household. 

Superannuitants experienced a 5.2 per cent increase in living costs. 

Beneficiary households experienced the lowest annual living-cost inflation of 4.8 per cent from December 2020 to the December 2021 quarter. 

"Beneficiary households typically spend a smaller proportion of their expenditure on petrol and interest payments when compared to the average household," StatsNZ said. 

Beneficiary households spend 2.1 per cent of their expenditure on interest payments, compared with 4.6 per cent for the average household.