Peter, the time pressure is that she recently got a very large promotion and raise. Buying years now means the purchase would be based on her lower salary and the payout would be based on her higher salary.Lower salary is 75k, higher salary is 115k. If we buy now, the cost of the years is as low as it will ever be. But the unpredictability of life is another strong rational for keeping the purchase money in an investment account vs. buying years. She has approximately 8 years left until retirement, but there's no way to know if she will serve all 8 of those years in the Colorado school system.So much to consider! I'm leaning toward a split decision buy a few years and invest the rest. But I'm still evaluating all the angles and ideas generated here from Fool replies.