Not sure exactly where to post this, but this seems to be the most reasonably place. When my husband was in the military, he didn't pay into the federal retirement system. Would it be worth it for him to make up that retirement investment in order to have those four years added to his total federal service? I think the amount we would have to come up with is around $2-3K. I don't think it will make any difference when he would retire, because he won't be at minimum retirement age when he hits 30, with or without the extra four years.