It used to be the case that those who were liable paid the Philippine departure tax (about 1,600 Peso) at the airport on departure from the Philippines. I flew one way from Manila to Kuala Lumpur a few days ago and noticed that Malaysia Airlines had applied a tax of $31.53 to my ticket for "Philippines International Travel Tax (PH)". I am British, had been in the country for less than two weeks and am not liable. At the airport the Philippine travel tax desk confirmed that I was not liable and could claim it back. They spent over ten minutes photocopying my passport and ticket, printing off and signing a myriad of internal documents, and generally looking very busy. End result, I have a refund receipt that I can present to the treasury division of one of their tax refund centres in Manila anytime in the next six months along with my passport, I will receive a crossed cheque in my name which I cannot use. Bloody useless!
