The taxes hangar is where you drop loot from large-scale PvP ops. If an op is lead by one of our major FCs, the loot will go into the taxes hangar. Theoretically, it is then sold to pay for ship losses or POS fuel.
To access the hangar, dock in a station where we have an office. From the station screen, click the "Corp Hangar" button, and then click the "Taxes" tab. You won't be able to view the contents of the hangar, but they're there, and you can just drag and drop the loot right into it. The loot will disappear and can only be removed by a director, who will probably steal it and sell it for personal profit.
Tip: To drag only a portion of a large stack of items, hold shift while clicking and dragging the item. A dialog box will pop up asking how much of the item you would like to move to the destination.