In accordance with IFRS 2, the expense related to share-based payments is recognized over the vesting period, with adjustments made for any changes in the estimate of the number of options expected to vest. In this case, Tucan granted 250 share options to each of 500 employees on 1 January 2016, with a condition that employees must remain in service for three years to be eligible to exercise the options. The fair value of each option is 15.

Tucan initially estimated that 50 out of the 500 employees would leave before the end of the vesting period, but by the end of 2016, only 15 had actually left. Despite this, the company still expects the same total of 50 employees to have left by the end of 2018.

To calculate the expense for 2016, we need to consider the number of options that are expected to vest in that year, which is 485 (500 - 50) out of the original 500. The expense for 2016 would be calculated as follows:

485 employees (remaining in service) * 250 share options per employee * fair value of each option ($15).

So, the expense for 2016 would be:

485 * 250 * 15 = 562,500

Therefore, the expense that will be shown in the accounts for 2016 is 562,500.