I bought back my time when I went regular about 12 years ago. I had been a sub for 14 years but also did clerk work as well. I had about 1 year and 8 months I could buy back. Can't remember for sure but it was about 3000.00. Paid it over a few months, if you decide to buy it back, do so as soon as possible. The amount continues to grow the longer you take. I am glad I did it but at the time, I thought it would add to my vacation days, not so. Only adds to computation for retirement years. I talked to someone in Personnel and they helped me out. Don't know who you talk to now. I tell all the old subs to at least check it out.