Calculating tax when there is an FYA

Good Afternoon!

in an apv question, i have run into a tax issue in my cashflow setup.

my method is to setup a workings table as follows:

operational net cash flow
(capital allowance)
———————————–
taxable cash flow

then i apply the tax rate and then subtract these taxes in my main setup of cashflows. tax payments lag by one year.

problem: my final cashflows for year 1 and the last year (yr 5) are wrong. (my computation of CA is correct and matches with the answer)

in this example, there is an FYA and i am applying this to year Zero and calculating the taxable CF. not sure if this is correct.

how do i use this method of minusing CA to cases where there is an FYA?

———————–

please note, i have solved the issue by taking tax savings on the CA and adding them to the cash flows. but i do want to know how to use the above method

thank u