Tandem holds the distinction of being one of the earliest UK challenger banks and one of the very few that reinvented itself successfully. Granted a banking licence in 2015, it spent its first years as a consumer app-based challenger without ever achieving the scale of Monzo or Starling, and its early history included the collapse of an investment that cost it its original licence and forced a restart through the acquisition of Harrods Bank.
The transformation came in January 2022 with the acquisition of Oplo, a consumer lender. The combined business had £1.2 billion in assets, over 171,000 customers and — critically — a lending book that made it profitable almost immediately. Alongside it came a strategic repositioning that has defined the bank since: Tandem rebuilt itself as the UK's greener digital bank, using competitive savings rates to fund green lending for home improvements, solar installations, heat pumps and electric vehicles. Further acquisitions followed, including green home improvement lender Allium and the money-sharing app Loop in 2023.
The strategy has produced consistent results. Tandem reported underlying profit of £24.1 million in 2024, up 40%, on revenue of £98.7 million and assets under management above £1.5 billion — a third consecutive profitable year and its first statutory profit. Green lending reached £572 million, 38% of total lending. 2025 delivered a fourth straight profitable year with £17.4 million in operating profit, and the bank reported more than £820 million in green and pathway-to-green home improvement funding to over 170,000 customers, with customers collectively saving an estimated 75,600 tonnes of CO2 during the year.
The proposition is genuinely differentiated in a way that most challenger bank positioning is not, because the green lending is the business rather than a marketing layer over a conventional one: savings deposits fund loans for measures that reduce household emissions and household bills at the same time. The risks are the ordinary ones for a consumer lender of this size — Tandem is a fraction of Monzo's scale, competes for deposits on rate against much larger balance sheets, and carries motor finance exposure at a time when the FCA's review of historic motor finance commissions has extended into 2026 with a compensation scheme pending. That last item is a live uncertainty for every UK lender with a motor finance book, and worth watching.