Q. If I retire at 58 this year, and don’t touch my TSP until I’m 60, does the IRS still withhold 20 percent for taxes?
A. Mandatory withholding from TSP distributions is not indexed to age, but to the nature of the distribution. See page 8 of the notice at https://www.tsp.gov/PDF/formspubs/tsp-536.pdf for a summary of the withholding requirements.