How credit card interest-free periods work, and what happens when they end

Key points

• "Up to 55 days interest free" describes the longest possible gap between a purchase and the due date it falls under. It isn't a window every purchase gets, and the date you buy something inside your statement period is what sets the length.
• Interest-free days on purchases depend on one condition: paying the closing balance in full by the due date. A minimum repayment is a partial payment, so it doesn't meet that condition.
• Any amount carried past the due date accrues interest, and on most credit cards new purchases then start accruing from the day they're made, until the account goes back to being paid in full.
• Promotional 0% and reduced-rate periods on purchases end on a set date, and whatever is still owing moves to the ongoing purchase rate that applies afterwards.
• Cash advances usually sit outside interest-free treatment altogether: interest from the day of the transaction, a separate higher rate, and a fee on top.

If your credit card advertises up to 55 days interest free, that number is accurate. It's also one of the easiest numbers on a credit card to misread, because it describes a best case rather than something every purchase gets, and the condition sitting underneath it is the part that decides what you actually pay. That condition isn't hidden. It's in your credit card contract, and most statements print it beside the due date. So here we go through what the number counts, the condition that switches it on and off, what happens when a promotional period ends, and why cash advances sit outside all of it.

What does up to 55 days actually mean?

It's the longest possible gap between a purchase and the due date it falls under, available only on a purchase made on the first day of a statement period (a purchase made on the last day of that same period gets 26 days, because all it has left is that day plus the payment window).

The window is made of the days remaining in the statement period from the day you buy something, plus the days between the period closing and the payment due date. The second part is fixed by your credit card, commonly around 25 days. The first part is whatever remains of the period, so the purchase date is what does the deciding. Below is one statement period with two purchases in it, one on day 1 and one on day 28. The dates are illustrative, the payment window is 25 days, and the counts include both the purchase date and the due date.

Both purchases sit on the same statement and share the same due date, so one gets 55 days interest free and the other gets 28. The day each one was made is the only thing that changed the window.

The date you buy something inside your statement period sets the length of its interest-free window. A purchase early in the period gets close to the number advertised, and a purchase near the end gets not much more than the payment window.

The condition that decides

Pay the closing balance in full by the due date and your purchases cost you nothing in interest (the closing balance shown on the statement, not the minimum repayment, and not just most of it).

Pay anything less and the arrangement changes. What you carry past the due date starts accruing interest, and on most credit cards new purchases begin accruing from the day they're made, with no interest-free window, until the account returns to being paid in full. So the effect isn't limited to the amount you left behind. Pay $1,950 of a $2,000 closing balance and the $50 left behind still counts as carrying a balance, so next month's spending can start accruing from the day you make it.

A minimum repayment doesn't meet the condition either. The smallest repayment that keeps the account in order is set by your provider under your credit card contract – commonly the greatest of any amount you're over your credit limit by, 2% of the closing balance, and around $25, and your statement shows yours. Whatever the formula, a minimum is still a partial payment, so the interest-free days stop applying while a balance remains.

In cost terms, a credit card cleared in full every month and the same credit card carrying a balance work as two different products, on one account, at one rate. How the interest is then worked out day by day, and how much of each repayment reaches the balance itself, has its own explainer.

Promotional offers and what happens at expiry

Some credit cards run a promotional period on purchases, either 0% or a reduced rate for a set number of months. Those run on their own rules, which are in the offer terms rather than in the ordinary interest-free days above, and the number worth finding first is the ongoing purchase rate that applies once the period ends. That's the rate any remaining balance moves to on the expiry date, and on an ordinary Australian credit card it might be around 20.99% (illustrative), which works out at 0.0575% a day.

So if you're going to use a promotional period, work backwards from the end date before you start spending. Divide what you expect to owe by the number of months in the offer, and treat that figure as the repayment you'd need to make each month for the balance to be gone by the expiry date. Then put that date in your calendar with a reminder a month ahead of it, because the date gets set at the start and it's easy to lose track of across a 12 or 18-month offer. Balance transfer offers work differently again, with their own transfer fee, offer period and revert rate, and they have their own explainer.

Pro tip: While a promotional period is running, connecting your accounts in WeMoney shows the balance and the repayments side by side, so you can watch the balance come down against the time left in the offer.

Cash advances sit outside all of this

Withdrawing cash on a credit card, and transactions treated as cash (some gambling and foreign currency purchases, for example), usually get no interest-free treatment at all. On most credit cards a cash advance starts accruing interest from the day of the transaction, at a separate cash advance rate that's typically higher than the purchase rate, with a cash advance fee on top. Paying the closing balance in full doesn't undo that interest, because the interest-free condition never applied to the cash advance in the first place. The exact treatment is in your credit card's contract, and how the charge is calculated is covered in the interest explainer.

Your own statement close and due date

Everything above runs off two dates that belong to your account and appear on every statement: the day the statement period closes, and the payment due date. Once you know them, you can tell whether a purchase is landing at the start of a period or the end of one, and how long you've got before the closing balance needs to be cleared. If the due date is the part that keeps catching you out, an automatic payment of the closing balance a few days beforehand means the date stops depending on you remembering (as long as the money is in the account on the day).

And if a promotional period has already ended, leaving a balance sitting at the ongoing rate alongside other debts, then whether reorganising those debts into a single repayment would help is a separate assessment, with its own place to be worked through properly.

Once your accounts are connected, WeMoney shows your credit card balances and repayments in one place, which makes it easier to keep the due date in view instead of finding out about it late.

Sources

• Moneysmart: Credit cards
• Moneysmart: Credit card calculator

This article provides general information only. It does not take your personal circumstances into account and is not financial, credit or legal advice. Consider your own situation and seek advice from a suitably qualified professional if you need it.