Hi Iain Wright,
Please have a look at SAIM5040 onwards (
Savings and Investment Manual) which advises that dividends are treated as paid for the purposes of the Corporation Tax Acts ‘on the date when they become due and payable’. The date when a final dividend becomes due and payable is usually established by a resolution of the company. The dividend becomes due when the date on which it is expressed to be payable arrives.
Thank you.