For years, federal employees who searched for a TSP Roth conversion hit the same wall: you couldn’t actually do one inside the Thrift Savings Plan. Your only path was to roll traditional TSP money out to a traditional IRA and convert it there. That changed on January 28, 2026. The TSP now lets you convert traditional balances to Roth right inside your account, and for a lot of feds chasing early retirement, it’s a big deal.
What actually changed
Starting January 28, 2026, the TSP added a Roth in-plan conversion feature. You can take any portion of your traditional (pre-tax) TSP balance and move it into your Roth (after-tax) TSP balance, all through your online account. No rollover to an outside IRA, no second custodian, no paperwork shuffle. The money never leaves the plan — it just changes tax buckets.
The mechanics are simple. You need at least $500 of vested money to convert, and you have to leave at least $500 in each traditional source (your own contributions and agency contributions are tracked separately) after the conversion. Beyond that, you choose the dollar amount. There’s no annual cap on how much you can convert the way there is on contributions — a conversion and a contribution are different things.
The tax catch nobody should skip
Here’s the part that trips people up. Every dollar you convert from traditional to Roth becomes ordinary taxable income in the year you convert it. Convert $40,000 and you’ve added $40,000 to your income that year, taxed at your marginal rate. There’s no penalty — a conversion isn’t an early withdrawal — but there is a real tax bill.
And you should plan to pay that bill with money from outside the TSP — a savings or brokerage account — not by having tax withheld from the conversion. Paying the tax with outside money is most of what makes a conversion powerful: it lets the full converted balance keep growing tax-free in the Roth. If you instead let the plan withhold, you shrink the amount that actually lands in the Roth and, if you’re under 59½, you can trigger a penalty on the withheld piece. Pay it from the side account.
Why this matters if you’re aiming for early retirement
The TSP Roth conversion isn’t interesting because it’s new — it’s interesting because of when a federal employee can use it. The golden window is the gap between leaving federal service and the year Social Security and required minimum distributions kick in. In those years your taxable income can be unusually low, which means your lowest tax brackets are sitting empty. Converting traditional TSP dollars to fill those cheap brackets — and only those cheap brackets — is the whole game.
Doing it early also shrinks the traditional balance that will eventually drive your RMDs. A big traditional TSP becomes big forced distributions in your 70s, often at higher rates than you’d pay now. Converting in your low-income years is playing defense against that. The logic is identical to the broader question of how much to convert to a Roth each year, and it pairs naturally with a Roth conversion ladder for tapping the money before 59½.
Watch the second-order effects
A conversion raises your income for the year, and income drives more than just income tax. A few things to keep on your radar before you click convert:
- It’s irreversible. Since 2018 you can no longer “undo” (recharacterize) a conversion. Once it’s done, the tax is owed. Convert deliberately, not impulsively.
- IRMAA. If you’re 63 or older, a big conversion can raise your Medicare Part B and D premiums two years later. The brackets are cliffs, not ramps.
- ACA subsidies. If you’re buying health insurance on the marketplace before Medicare, conversion income can cut your premium tax credit.
- The 5-year clock. Each conversion starts its own 5-year clock for penalty-free access to the converted principal before 59½.
None of these are reasons to avoid converting. They’re reasons to size each year’s conversion on purpose — usually up to the top of a target tax bracket — rather than converting a giant lump in a single year.
What it looks like in practice
Say you retire from federal service at 57 with $700,000 in traditional TSP and little other income until Social Security at 67. In each of those bridge years you could convert just enough to fill a target bracket — say up to the top of the 12% bracket — paying a modest, predictable tax bill from your savings. Ten years of that can move a large share of the balance into Roth at low rates, well before RMDs would have forced much larger taxable distributions at 73 or 75. A market dip is an especially good moment: converting while the funds are down means you move more shares into Roth for the same tax bill, and all the recovery happens tax-free. The goal isn’t to convert everything — it’s to convert the cheap dollars and stop.
Does the in-plan conversion replace rolling out to a Roth IRA?
Not entirely. The in-plan conversion is simpler and keeps your money in the TSP’s famously low-cost funds. But a Roth IRA still offers a far wider menu of investments and easier estate planning. One wrinkle worth knowing: thanks to SECURE 2.0, Roth balances inside workplace plans like the TSP no longer carry required minimum distributions starting in 2024, so a Roth TSP is no longer at a disadvantage there. For many feds the answer is a mix — convert in-plan during low-income years for simplicity, and roll to a Roth IRA later if you want more control.
The bottom line
The TSP finally caught up to what private 401(k) plans and IRAs have offered for years. If you’re a federal employee with a large traditional balance and you’re heading into a stretch of low-income years, the in-plan conversion is a clean, powerful tool — as long as you respect the tax bill and convert in measured, bracket-aware amounts. The official details are on the TSP’s announcement page.
This is educational, not tax advice. Conversions are irreversible and the right amount depends entirely on your own numbers — run it past a tax professional before you convert.
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