Basis of assessment

Hi , I have a question .

When calculation the basis of assessments, lets say for example we get to year 2 and there is no accounting period that ends in tax year 2. Do we take the full amount and label its as (6/4 to 5/4). I have made up an example below :

Tax payer commences to trade on the 1st Jan 2015 and prepares accounts to :

Period 30.03.15 £30,000
Y/e 30.03.16 £48,000
Y/e 30.03.17 £50,000

2014/15 – Actual
(01/01/15 – 05/04/15) = £30,000

2015/16 – Tax year
(06/04/15 – 05/04/16) = £48,000

2016/17 – CYB
(Y.e 30.03.17) = £50,000

Is this how you would handle an accounting period which does not end in tax year 2? Would you have answered this question differently ? and Have I understood CYB correctly?

Thank you in advance 🙂