No money isn't post-TOS, I'm pretty sure.
The idea first cropped up in Star Trek IV: The Voyage Home. The Original Series made numerous references to money and even had the scene with Uhura haggling with Cyrano Jones to buy a tribble on Space Station K-7. Voyager later retconned the demise of money to the 22nd century in the episode "Fury". Then Kirk offered to pay for Uhura's drink in Star Trek (2009), re-un-retconning it. Sort-of.