TXA starting rate of 0% applies to savings income

Adam owns a residential property that he lets out. During the tax year 2024/25 he received rent of £15,000 and paid the following expenses: £ Agent’s fees 1,000 Insurance 1,500 Gardener’s costs 1,300 Interest costs on loan to acquire property 7,500 During the tax year 2024/25 Adam also has trading income of £42,000 and bank interest income of £800. Calculate Adam’s income tax liability, after reliefs, for the tax year 2024/25. Solution Non- savings income Savings income Total £ £ £ Trading income 42,000 42,000 Property income (W) 11,200 11,200 Bank interest 800 800 –––––– ––––– –––––– Total income 53,200 800 54,000 Less: PA (12,570) (12,570) –––––– ––––– –––––– Taxable income 40,630 800 41,430 –––––– ––––– –––––– Income tax £ £ Non-savings income – basic rate 37,700 × 20% 7,540 Non-savings income – higher rate 2,930 × 40% 1,172 –––––– 40,630 Savings income – nil rate 500 × 0% 0 Savings income – higher rate 300 × 40% 120 –––––– 41,430 –––––– ––––– 8,832 Less: Basic rate tax relief on property income interest (£7,500 × 20%) (1,500) ––––– Income tax liability 7,332 QUERY In this solution, they have considered the first £ 500 of bank interest income to be entitled to savings income nil rate band. Why have they done this? This £ 800 doesn't fall within the first £ 5000 of taxable income. It doesn't follow the rule. A starting rate of 0% applies to savings income where it falls within the first £5,000 of taxable income. I am confused.