Q. I worked from October 1985 to April 1991 for the post office and was part-time flexible for 13 months of it. I cashed out my retirement when I left. If I took a federal job, would I be allowed to buy that time back for retirement? Also, if that job was not with the Postal Service, would this affect retirement benefits? A. If you return to work, you could redeposit that money, plus accrued interest. It doesn’t make a difference whether you work for the Postal Service or any other federal agency. They’re all under the same retirement system.