Credit Simple chief executive David Scognamiglio said New Zealanders sometimes missed payments or paid bills late as they began to feel the effects of a Christmas debt hangover.
"The jump from 6.4 to 7.6 per cent in overdue credit card repayments might not sound big, but in a nation with $6.6 billion outstanding on credit cards, that little extra interest-incurring period adds up to millions in extra interest payments for consumers."
It can also damage a person's credit score putting them at risk of not being able to borrow in the future or having to pay a higher interest rate.
"Late or missed payments on any borrowed funds will damage your credit score and could prevent you from getting credit again, so it's crucial to make a plan to pay back and credit consistently and on time to keep your credit score healthy."
Kiwis pay interest on around 63 per cent of the outstanding credit card debt and the average interest rate on outstanding balances was 18 per cent last year.
Financial rating firm Canstar estimates Kiwis put around $36b on the plastic last year of which $22.9b would attract interest equating to more than $4b in interest payments.
Canstar general manager Jose George said it was important for consumers to make the right decisions about which credit cards they use.
"Credit card interest rates currently range from 12.69 per cent to 25.99 per cent. Choose the wrong card and it could have a massive impact on how you can manage your daily finances."
George said consumers needed to consider what kind of user they were when choosing a card.
Those who make a part payment or make the minimum balance payment should focus on low interest rate credit cards while those who use their credit card for emergencies should look at low or no fee cards.
People who pay off their credit card in full should also look at how much they are paying in annual fees and can take rewards into account.
George said if managing existing credit card debt was an issue it was a good time to look at the options and consider transferring a balance from an existing card to one with a more favourable rate.
"Be careful to check when and how the transferred balance will attract interest and as with paying off any debt, discipline in paying off the balance is key."