2.4 Taxation of Non Savings, Savings and Dividend Income - Example 10 query

Hello, In the lecture video titled "2.4 Taxation of Non Savings, Savings and Dividend Income" - at around 46:00 into the video when the lecturer is working through Example 10 - I have a query on these workings. The lecturer notes that a £500 nil-rate band allowance is available for a higher rate tax payer, then in the calculations, £37,700 of Non-Savings Income is taxed at 20%. I thought that as the £500 nil-rate band was being used, then this meant £500 was used towards the £37,700 Basic Rate threshold? (Meaning that only £37,200 would be taxed at 20% - and this would push an extra £500 of Non-Savings Income into a 40% tax rate). Or is it as the entire £37,700 of the Basic Rate threshold is used in Non-Savings Income this is calculated before considering the £500 nil-rate band Savings Income allowance? Here is a summary of the lecturer's workings: Non Savings Income: £37,700 x 20% = £7,540 £54,730 x 40% = £21,892 Savings Income: £500 x 0% = £0 £3,500 x 40% = £1,400 Tax Liability = £30,832 But here are my workings (based on using £500 nil-rate band in the £37,700 threshold): Non Savings Income: £37,200 x 20% = £7,440 £55,230 x 40% = £22,092 Savings Income: £500 x 0% = £0 £3,500 x 40% = £1,400 Tax Liability = £30,932 Which is correct and why? Hopefully my question makes sense - apologies for making it so long winded. Thank you for your help. Charley