Q. I am a 66-year-old female who retired in January 2007, with more than 30 years Civil Service Retirement System service. I am thinking of withdrawing my Thrift Savings Plan savings. I understand that I will not be penalized the 10 percent, and I would have to pay the mandatory 20 percent if I decide to withdraw. Does the 20 percent also apply at age 70½? Does this also apply to partial withdrawals, and do you have to pay back if you do a partial? Is the amount taxed by the Internal Revenue Service on your entire TSP earnings? What percentage would IRS use?