By Chris Dorrell Tandem Bank reported a second consecutive year of profitability in 2023 as customers flocked to the challenger’s greener offering. Underlying profit at the digital challenger increased five-fold, jumping to £17.2m in the 2023 financial year from only £3.6m last year. This was largely driven by a big improvement in its net interest income, the difference between what banks receive and pay out in interest payments. Net interest income jumped 28 per cent, from £68.5m to £87.8m. Many lenders have seen the benefit of higher interest rates, which currently stand at a post-financial …