For Thai income tax purposes, the trip to Hong Kong is treated as a benefit in kind and therefore subject to personal income tax.
However, the Management Board approved to have the firm absorb the personal income tax. Therefore, in your June 2016 salary payslip, under Income, you will see a certain amount of the tour package costs in Transport and Housing, and the amount of absorbed personal income tax in Other Income.
Also, if you have a mobile phone allowance and benefit menu claim, these will be included in Other Incomeas well.