Are credit card surcharges ever illegal?

A surcharge is typically legal in Australia, as long as the merchant can prove that it covers the reasonable cost of acceptance and has clear notices about the surcharge before you pay.

What protection is there against high surcharges?

In 2016, the Australian government introduced an excessive surcharge ban to make sure customers weren't paying more than what it cost to process the payment: the Competition and Consumer Amendment (Payment Surcharges) Act 2016 . This ban applies to payments made by EFTPOS, Visa, Mastercard and American Express "companion cards" (Amex cards that used to be issued by some banks). It does not technically apply to American Express cards directly issued by American Express, as well as Diners Club, BPAY, PayPal, UnionPay, cheques or cash. But it does help protect you against high surcharge costs. If you think a business is charging too much for card payments or other payment methods, talk to the business or contact the ACCC on 1300 302 502.