Actively employed TSP participants age 50 and older can make TSP catch-up contributions of an amount ($6,000 in 2017) above the elective deferral limit amount ($18,000 in 2017). Catch-up investments can be made under either the traditional TSP design or under its Roth design or both, so long as the total amount invested is within the catch-up limit.
TSP Catch-Up Contributions Eligibility
In order to be eligible a participant: must be in pay status (that is, not on leave without pay, retired or otherwise separated); must be contributing a biweekly amount which will result in his or her reaching the elective deferral limit by the end of the relevant year (or have reached that limit already); must be at least 50 years old in the year the catch-up contributions are made (even if the participant’s birthday is December 31 of that year); and must not be in the six-month non-contribution period following the receipt of a financial hardship in-service withdrawal.
Eligible persons may elect to make catch-up contributions in whole dollar amounts per pay period, up to the annual limits on catch-ups under the tax law. Catch-up contributions can be started at any time, not just during one of the twice-yearly open seasons. Catch-ups have to be made from payroll withholding; the individual cannot write a check and send it to the TSP. Also, those wishing to make the contributions have to fill out a new election form each year. The form to use is TSP-1-C, Catch-up Contribution Election.