If you prefer to keep your money inside the TSP, there is a two-step workaround you can use to mimic a single-fund withdrawal. Image: Gannvector/Shutterstock.com When you reach retirement and finally begin drawing down your Thrift Savings Plan (TSP), you might assume you have complete control over where that money comes from. Unfortunately, that is not the case. Under current TSP rules, whenever you take a withdrawal, the money is pulled proportionally from every fund you are invested in.