I've just seen this (https://www.onlinegar.com/support.olg?opt=whereitgoes) which says that for IOM you need to fill out the form using Online GAR site and send it to them manually.

Thanks - Departing from Newcastle EGNT which is customs. It is more the fact that IOM require a copy of the GAR to be sent direct to them as they report they don't receive electronic copies submitted by other methods. 

thanks. 

I you're flying from a designated airport then a GAR is not required and the option will not be shown. Try changing your dearture airport and see if the GAR option appears again. Where are you flying from?

Take a look at https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/412944/GAR_Instructions_March_2015.pdf

Planning to visit the IOM for the TT end of next week and wanting to file GAR. I recall when i went last year, the option to file from SD under "flight details" section was there but doesn't appear now? 

Has this changed since last year - and if not, where can i find it? 

thanks.