Age-. The general rule in the industry is that once an A/C unit reaches 10-15 years, the idea of replacing the unit is usually a much better investment than putting money into an older system. If your system is at this threshold, it's usually wise to begin expecting, not wondering, when the system will fail.
You can keep the money in the TSP after you leave your federal job to benefit from the low fees, or you can roll over the money into an IRA or a new employer's 401(k), 403(b) or 457.
You may enroll in the TSP at any time via myPay. If you are a new employee and do not have a myPay PIN, you may complete a TSP Election Form (TSP-1) and submit it to the Benefits and Payroll Liaison Branch in Building 31, Room B3C23. Once your TSP account has been established, changes in your contributions can be done at any time through myPay. Changes to your allocations must be done through TSP Account Access on the TSP web site or by calling the ThriftLine (1-877-968-3778).