The investments MUST be made before the company year end of the year in which corporation tax is to be relieved. This means that you should ensure that your accountant has, within the final month, a very good idea as to corporate profits. The other area to review is the remuneration basis. I once saved tax for a client by increasing his salary from 60,000 to 120,000 pa. The eventual routine should be, in the final month or so of the company year, with cash awaiting investment, to review anticipated profits and remuneration, then doing a computation to strike the most tax efficient balance to use the funds available.
Clear diaries are essential.