The value of spending on electronic cards fell by 0.7% during December.
According to Statistics New Zealand, there was a fall of 2.9% in November.
A Bank of New Zealand economist says the fall in spending is dissapointing given falls in petrol prices and interest rates.
The BNZ says it expects consumer spending to have fallen 1% in December compared to the previous month.
Figures earlier this week showed an increase of 0.1% in retail spending in November.