Calculation of Gain/Loss of Foreign Savings Insurance with Life Cover Policy

I had a savings insurance with life cover policy matured in Thailand. Is the calculation of gain and loss completed by using the formula of Total Benefit less Total Deduction (the total premium paid) and less Previous Gains (the amount of money back every 4 years)? OR is chargeable event gain/loss based on the final amount of payment I received from the insurer at maturity?

Hi Kelvin,
Plese refer to guidance here:
HS321 Gains on foreign life insurance policies (2023)
Thank you.