UK adults are forecast to pay £16.9 billion in credit card interest in 2026, equivalent to roughly £300 per person. None of that money reduces the underlying balances. Every pound services interest rather than paying down what was borrowed. Total UK credit card debt is on track to hit £79 billion by the end of 2026, and on current growth rates, annual UK credit card interest payments are projected to reach £25 billion by 2037.