Most people will acquire things while overseas, so it is logical that what you bring home could weigh more than what you took over there. Are you also aware that when calculating your entitlements, they include the weight of both the stuff you're bringing home as well as the stuff you left in storage in Canada? The CF only pays to move a total of 20,000 lbs out of core, regardless of whether it's in storage or overseas. If the total weight of what's in storage (which has to be moved somewhere when you get home), plus the stuff you're bringing home from overseas, exceeds 20K lbs, then you have to pay the difference in cost out of your custom and personal envelopes.