The Federation of Family Budgeting Services says the fact people are using credit, debit and charge cards to buy food and fuel suggests household budgets are stretched.
Retail spending using credit, debit and charge cards was 0.1 percent higher in April than March, mainly because people spent more on petrol and foodstuffs. Spending on clothing and footwear fell.
Federation chief executive Raewyn Fox said the data confirmed what budget advisers know: that many people have little money left after the essentials are bought.
She said the use of credit cards to pay for essentials carried the risk of putting people further into debt.