TQOTW: ANNUAL INVESTMENT ALLOWANCE (AIA)

My client company has a year-end of 31st May 2019 and throughout the year the company incurred capital expenditure that qualifies for the annual investment allowance (AIA). How do we determine the amount of AIA available and how do we allocate the AIA to the qualifying expenditure given that the amount of AIA went up from £200,000 to £1m in January 2019?