CardUp charges you a transaction fee for each payment made.

Every transaction you complete using CardUp will incur a 2.6% transaction fee. This can actually add up over time, especially if you’re relying heavily on CardUp. That being said, if your card offers cash rebates or frequent flyer miles, you may easily be able to offset the transaction fee. CardUp works by being a middleman in your transactions. Instead of directly transferring funds from your account to a vendor, you pay CardUp via credit card. CardUp will then transfer the funds to your designated vendor. CardUp charges you a transaction fee for each payment made.