Joseph Kent started business on 1 October 2021 as a joiner making conservatories. His tax-adjusted profits (before deduction of capital allowances) were as follows:

Capital additions and disposals were as follows:

Private use of both cars has been agreed with HM Revenue and Customs at 20%. No claim is made to treat any of the assets as short-life assets.

Joseph's wife Sephora is a solicitor employed by a practising firm at a salary of £51,850 per annum. The following additional information is provided for 2023-24:

(i) A new petrol-engined car was provided for Sephora's use in August 2022. The list price at that time was £22,800. Of this amount, £4,000 was contributed by Sephora so that a better car could be provided. She was required to pay £25 each month towards the private use of the car but not towards the private fuel, all of which was provided by her employers. The car has an emission rating of 103g/km.

(ii) Sephora has received a loan of £90,000 on the matrimonial home from her employers on which she pays interest at 0.5% per annum.

(iii) On 1 July 2023, Sephora made a qualifying donation to a UK charity of £400 under the Gift Aid scheme.

(iv) Both Joseph and Sephora were born in 1984. They are not Scottish taxpayers.

You are required:

(a) To calculate Joseph's trading income for 2021-22 to 2023-24 inclusive.

(b) To calculate Sephora's income tax liability for 2023-24 (assuming an official rate of interest of 2.25%

per annum).