Looking at adding hold luggage to my booking made a few weeks ago, I noticed it had an option to add hold luggage on outbound and inbound legs. Does that mean I have to book both legs separately or does booking the outbound leg automatically include luggage on the inbound leg.
easyJet regards each flight as an entirely separate booking. Further, they've no way of knowing whether you'll want to carry the same stuff in each direction. (Some people might fill their outbound bags full of Marmite to deliver to ex-patriot friends but return with hardly anything. Others might travel out with very little but need to book hold space on the return journey for all of their souvenirs).
You need to book hold luggage for both directions (and thus pay twice).
Chris, as you'll doubtless have heard, you'll shortly be able to get carry-on-compliant Marmite in containers of less than 100ml, for those who can't be parted from it...
Not just easyjet, I think all airlines treat them as 2 separate journeys and yes you to have pay for both ways. Normally if you are booking a return flight and add hold luggage it will be on both flights but the cost is automatically doubled so if a hold bag costs £15 you'll have £30 added to the price - purely as example.
I have more than once wanted to take along a checked in bag on the outward leg only on a booking made as a return journey. In every case "adding a bag" was going to mean a 2xbaggage-charge card debit and a note on the booking that I would be carrying 20kg each way. To book and pay for the bag in one direction only required a phone call to easyjet. Unless easyjet have changed their system, it is not possible to do a single direction bag addition and the quoted fee will be for both legs (out and return). Obviously, if the two journeys were booked separately (i.e. not as "return" on that leg) then they would count as two separate journeys and would likely carry two separate booking references - and a bag can be added for each of these.