The rate at which Interest is accumulated in the game is based on the number of cores that are sitting in the housing. There are 24 cores in total and if they are all present and in the housing, full interest is earned on the amount of resources you have at that time. Interest payments are calculated every 2 seconds and then added to your total resource amount.
While one or more of the cores are away from the housing 1/24th of the interest is not earned until the core is returned.
Interest is every 2 seconds at standard speed.
Interest per tick = Cores in housing * 0.0001 * current resources.
Source: http://defensegrid.hiddenpath.com/node/581
Fredrik 'Grey Fox' Henriksson is an avid Civilization and StarCraft 2 player as well as a wannabe game designer. When he isn't playing games or working on mods he likes to paint digital art, watch tv-series, a movie or just hang with good company.