Q. I will be 66½ when I retire with 15 years of federal service. How long can I leave my money in TSP until I am forced to take it out?  Will I have to pay taxes on it when I am forced to withdraw, and is there a penalty accessed? A. You must begin taking withdrawals – called Required Minimum Withdrawals  – by April 1 of the year following the calendar year in which you reach age 71½. Visit www.tsp.gov for more information.