Before You Convert Inside the TSP — What They Don’t Always Tell You
If you’ve read Parts 1 and 2 of this series, you already know that the new in-plan Roth conversion feature that came to the TSP in 2026 is a genuinely exciting development for federal employees. The ability to convert pre-tax dollars to Roth without ever leaving the TSP is convenient, familiar, and low-cost. But convenience isn’t always optimal, and for many Feds, converting within the TSP rather than outside may entail trade-offs worth understanding before you act.
This isn’t an argument against in-plan conversions. It’s a reminder that the right tool depends on your situation, and that the TSP’s new feature, powerful as it is, isn’t necessarily always the best path forward.
The TSP’s Investment Menu Is Still Limited
One of the most significant differences between converting inside the TSP versus rolling funds to a Roth IRA outside the plan is investment flexibility. The TSP offers five core funds and a handful of Lifecycle funds a simple, low-cost lineup that works well for accumulation. But in retirement, when you’re managing withdrawals, tax exposure, and income timing simultaneously, that limited menu can become a constraint. Outside the TSP, you have access to a much broader range of investment options, enabling more precise income planning and portfolio customization. If your retirement strategy requires more than what the G, F, C, S, and I funds offer, staying inside the TSP for your Roth dollars may not serve you as well as moving them out.
The Allocation Problem: One Size Does Not Fit All
There’s another layer to the investment limitation worth understanding: inside the TSP, your traditional and Roth balances must be allocated identically. Whatever percentage you assign to the G, F, C, S, and I funds applies across both balances. You cannot, for example, hold your traditional TSP in more conservative funds while investing your Roth TSP aggressively in equities. In sound retirement planning, that distinction matters quite a bit. Because Roth dollars grow tax-free and are intended for the long term, often the last dollars you’ll touch in retirement, they arguably deserve a more growth-oriented allocation than your traditional balance, which may be drawn on sooner and taxed as ordinary income. Outside the TSP, in a Roth IRA, you have complete freedom to allocate each account independently based on its purpose, time horizon, and role in your overall income plan. The TSP’s one-size-fits-all allocation approach isn’t a flaw for everyone. Still, for Feds who want to manage their traditional and Roth dollars as distinct pools with different jobs to do, it’s a meaningful constraint that converting outside the plan can solve.
Withdrawal Flexibility Is Still More Restricted Inside the TSP
Even after the launch of in-plan conversions, the TSP’s withdrawal rules remain less flexible than those governing a Roth IRA. With a Roth IRA, you can withdraw your contributions, not earnings, but the principal at any time, for any reason, without taxes or penalties. That’s not the case inside the TSP, where more rigid rules govern withdrawals, and your Roth and traditional balances are generally distributed proportionally rather than selectively. For retirees who want precise control over which dollars they pull and when, the TSP’s structure can make that harder to execute cleanly. Converting outside the TSP preserves that granular control.
IRMAA: The Hidden Cost of a Large Conversion
Whether you convert inside or outside the TSP, the tax hit is real, but it’s not just income tax you need to watch. Converting a significant amount in a single year raises your Modified Adjusted Gross Income (MAGI), which can trigger IRMAA surcharges on your Medicare Part B and Part D premiums. These surcharges are applied on a two-year lookback, meaning a large conversion in 2026 could increase your Medicare premiums in 2028. For federal retirees already drawing a FERS annuity and Social Security, there may not be much room to convert before crossing an IRMAA threshold. This isn’t a reason to avoid conversions entirely, but it’s a critical calculation that must be done before deciding how much to convert and in what year.
Your FERS Pension and Social Security Drawing Strategy Complicates the Math
Many articles about Roth conversions are written with private-sector workers in mind, where retirement income is more variable and controllable. Federal employees face a different reality: your FERS annuity provides a guaranteed, taxable income stream from day one of retirement. Add Social Security and many Feds find they’re already in a moderate to high tax bracket before ever touching their TSP. That changes the calculus significantly. The window for low-bracket conversions may be narrower than you expect, potentially limited to the gap between your FERS start date and when Social Security begins, or before RMDs kick in at age 73. Outside the TSP, a Roth IRA conversion can be coordinated more precisely around these income events. Inside the TSP, the mechanics are simpler, but the planning still requires the same level of care.
State Taxes Vary, and the TSP Doesn’t Account for Them
The TSP operates at the federal level, and its conversion feature is designed around federal tax rules. But depending on where you live, your state may tax Roth conversions just like ordinary income. Some states exempt TSP or pension income; others don’t. If you’re planning to relocate in retirement a common move for Feds converting inside the TSP now- in a high-tax state, when you could wait and convert in a lower-tax or no-income-tax state later, may cost you unnecessarily. This is a nuance the TSP’s conversion tool won’t flag for you, but a financial planner familiar with federal benefits will.
The Five-Year Clock Runs Independently and Can Catch You Off Guard
Every in-plan conversion starts its own five-year holding period before the converted earnings can be withdrawn tax-free. If you make multiple conversions over several years, which is often the smart approach, you’ll be managing multiple clocks simultaneously. Miss the timing on a withdrawal, and you could face unexpected taxes or penalties on earnings, even from a Roth account. Outside the TSP, in a Roth IRA, the five-year rule is generally measured from the first year you ever contributed to any Roth IRA, which can work in your favor if you’ve had a Roth IRA open for years. Inside the TSP, each conversion stands alone. This isn’t a dealbreaker, but it requires careful tracking — especially for Feds who retire early and need flexibility in those first years.
The Bottom Line
The in-plan Roth conversion feature is a meaningful step forward for the TSP, and for many federal employees it will be the right choice. But “available inside the TSP” doesn’t automatically mean “better than the alternative.” Rolling funds out of the TSP and converting to a Roth IRA outside the plan still offers advantages in investment choice, withdrawal flexibility, and coordination with your broader retirement income picture.
The smartest approach isn’t choosing one path and committing unquestioningly — it’s understanding both options well enough to use each one where it potentially fits best. For some Feds, that might mean partial in-plan conversions to keep things simple, while maintaining a separate Roth IRA for flexibility. For others, the outside route may still be the better long-term play.
Either way, this decision deserves more than a few minutes of thought. Model the scenarios, account for your pension, Social Security, Medicare premiums, and state taxes, and if you’re not sure, work with someone who understands the full picture of federal retirement.
Prepare. Plan. Prosper.
Wes Battle CFP®, ChFEBC℠, AIF®, RICP® proudly hails from a Fed family. Beginning with his grandfather, their service to the country reaches back 70 years. Wes brings nearly two decades of financial experience to his service to federal employees and works to treat them as family.
James "Wes" Battle is a Financial Planner - Securities offered through Cetera Wealth Services, LLC, member FINRA/SIPC. Advisory Services offered through Cetera Investment Advisers LLC, a registered investment adviser. Cetera is under separate ownership from any other named entity. 2101 Gaither Rd., Ste 600, Rockville, MD 20850. The opinions contained in this material are those of the author, and not a recommendation or solicitation to buy or sell investment products. This information is from sources believed to be reliable, but Cetera Wealth Services, LLC cannot guarantee or represent that it is accurate or complete. For a comprehensive review of your personal situation, always consult with a tax or legal advisor. Neither Cetera Wealth Services, LLC nor any of its representatives may give legal or tax advice.
All investing involves risk, including the possible loss of principal. There is no assurance that any investment strategy will be successful. Converting from a traditional account to a Roth account is a taxable event. A Roth account offers tax free withdrawals on taxable contributions. To qualify for the tax-free and penalty-free withdrawal or earnings, a Roth IRA must be in place for at least five tax years, and the distribution must take place after age 59 ½ or due to death, disability, or a first-time home purchase (up to a $10,000 lifetime maximum). Depending on state law, Roth IRA distributions may be subject to state taxes. A diversified portfolio does not assure a profit or protect against loss in a declining market. Tax Free - Income may be subject to local, state and/or the alternative minimum tax. Before moving assets from an employer-sponsored retirement plan, investors should carefully consider all available options, including remaining in the current plan, rolling assets to another employer plan, rolling assets to an IRA, or taking a distribution. Differences in investment options, fees and expenses, services, creditor protections, and distribution rules may apply.