Readers’ forum: Calculating taxable amount for transitional period

I welcomed Simon Groom’s comprehensive two-part series on basis period reform: ‘The basics of basis period reform’ (Taxation 11 April 2024 and 18 April 2024). I am having difficulty getting my head around some parts of it however and I would like readers’ takes to help to get additional clarity.

Take ‘Illustration 2’ in part 2 of the series (‘Gareth’). The standard profit is £36 000. The transition part of the basis period is 1 October 2023 to 5 April 2024.

Rather than take 6/12 x £54 000 (profit to 30 September 2024) which means waiting until later in 2024 could I calculate the profit now from 1 October 2023 to 5 April 2024? That would be the transition part (step 3). Deduct the £6 000 overlap from that. Add that result to the £36 000 (step 4).

On to step 5: take the lower...