I played a small map and only had a few planets and had few credits coming in so i researched the colony pods for the vasari star base and qued up both my starbases with double colony pods.  After they were finished researching/building, the info card for the starbase showed the increased population (100 or so population) however i did not receive any additional income.  When i hover the mouse over the credits on the top of the main hud, the planet and credit breakdown did not show any change in the planets income nor did it change my starbase trade port income amount.  I installed the colony pods on two starbases which were over volcanic planets to where the population on the starbase exceeded the population on the planet (70 pop) but i wasn't receiving any additional credits Also visually counting my credits come in per second confirmed that the extra colony population doesn't yield any taxable income. 

For fun i setup a mock game with retard AI's.  I built up 6 planets with full population upgrades and population increase researches.  I let the game sit while defending but not modifying my credit/resource intake or creating trade alliances.  I slowly built starbases and once i had enough cash i dropped double colony pods on all 6 starbases to where they completed simultaneously.  I waited an additional 20 minutes and still there was no income increase.