A 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.