What Are the Roth TSP Contribution Limits?

The Thrift Savings Plan (TSP) offers a Roth option for federal employees and members of the uniformed services to save for retirement. This plan allows you to make after-tax contributions, meaning you pay taxes on the money now so that qualified withdrawals in retirement are tax-free. Understanding the rules that govern how much you can contribute is an important part of maximizing this benefit, as the regulations have several components.

The Elective Deferral Limit

The Internal Revenue Service (IRS) sets an annual elective deferral limit on employee contributions to retirement plans. For 2025, this limit is $23,500. This cap is shared between your Roth and Traditional TSP accounts, meaning the combined total of your contributions cannot exceed this amount.

This structure allows you to allocate your savings based on your financial strategy. For instance, a federal employee could contribute $15,000 to their Roth TSP and $8,500 to their Traditional TSP in 2025. It is your responsibility to monitor bi-weekly contributions to ensure you do not exceed the annual limit.

The elective deferral limit is subject to cost-of-living adjustments by the IRS. Contribution elections are made through your agency’s payroll system and will carry over into the new year unless you make a change.

Participants under the Federal Employees Retirement System (FERS) should plan their contributions to last the entire year. If you reach the elective deferral limit before the final pay period, you will miss out on agency matching contributions for the rest of the year. Spreading your total desired contribution evenly across all 26 pay periods prevents this.

Catch-Up Contribution Rules

Participants age 50 or older can make additional catch-up contributions above the standard elective deferral limit. For 2025, the catch-up contribution limit is $7,500. This allows an eligible participant to contribute the $23,500 elective deferral plus an additional $7,500, for a total of $31,000.

The TSP uses a “spillover” method for these contributions, which simplifies the process. Eligible participants do not need to make a separate election for catch-up funds. Once regular contributions reach the annual elective deferral limit, subsequent contributions automatically count toward the catch-up limit until it is also met.

A provision in the SECURE 2.0 Act of 2022 creates a higher catch-up limit for certain participants. In 2025, participants turning ages 60, 61, 62, or 63 have a higher catch-up limit of $11,250. This allows these individuals to contribute a total of $34,750 for the year.

Uniformed service members in a designated combat zone have different contribution rules. They may be able to make additional contributions from tax-exempt combat pay, which are subject to a separate annual limit defined by the IRS.

The Annual Additions Limit

The annual additions limit is a broader cap on the total contributions from all sources to a participant’s account in one year. For 2025, this overall limit is $70,000, or 100% of the participant’s compensation, whichever is less.

This limit includes all employee contributions (Roth, Traditional, and catch-up) and all employer contributions. For FERS employees, this includes the agency’s automatic 1% contribution and any agency matching contributions.

While an employee aged 50 might personally contribute up to $31,000 in 2025, the annual additions limit ensures that the sum of their contributions plus all agency contributions does not exceed the $70,000 threshold. This limit is most relevant for higher-income employees or members of the uniformed services making large contributions.

Coordinating TSP Contributions with Other Accounts

The $23,500 elective deferral limit is a per-person limit, not a per-plan limit. The cap applies to the combined total of contributions made to all similar employer-sponsored retirement plans, such as a 401(k) or 403(b). If you have a TSP and another employer’s plan, you must coordinate your contributions.

For example, if you contribute $10,000 to a civilian 401(k) in 2025, you can only contribute a maximum of $13,500 to your TSP that year. The responsibility for monitoring this combined limit rests with the employee, and over-contributing can lead to tax penalties.

A common point of confusion is the difference between a Roth TSP and a Roth IRA. While both offer tax-free growth, they are governed by different rules. The ability to contribute to a Roth IRA is subject to income limitations set by the IRS. In contrast, the Roth TSP has no such income-based restrictions, allowing any eligible federal employee or service member to contribute regardless of income.