4. How do I increase (or decrease) my contribution to the TSP?

You can change the amount of your pay that you are contributing to the TSP only during an open season. However, if you are a member of the uniformed services, you may also change your contribution amount within 60 days of a status change from active duty to Ready Reserve, or vice versa.

If your agency or service has an electronic personnel/benefits system, such as Employee Express, PostalEASE, or myPay, use it to increase or decrease the amount of your pay you want to contribute to the TSP each pay period. Enter your new contribution amount as a dollar amount or a percentage of your pay for a civilian account, or as a percentage of pay for a uniformed services account. If your agency or service does not have such a system, you can print out a copy of the TSP Election Form TSP-1(Form TSP-U-1 for members of the uniformed services). Fill it out and submit the form to your agency personnel or payroll office. Do not send the form to the TSP.
PS System wouldn't let me "REPLY" to post.