From the horses mouth (APD Helpdesk):
UK Ministers announced in 2011 that APD would be extended from its current form to include smaller aircraft from 01 April 2013. It was to include both private and corporate aircraft.
The Notice 550 on our website is not yet the one that will apply from 01 April 2013, when the UK air passenger duty (APD) is extended to include aircraft of a certified weight above 5.7MT.
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