Is Roth or traditional TSP better?

It comes down to one comparison: the tax rate your traditional contribution saves you today against the tax rate you expect to pay when you withdraw. If your retirement rate will be higher, Roth wins. If it will be lower, traditional wins. The break-even point is the rate the deduction actually saves you now, and this calculator computes that figure from the 2026 brackets in IRS Rev. Proc. 2025-32 rather than guessing at your bracket. Years until retirement and your expected return do not change the break-even, because they scale both sides of the comparison equally, as long as the same dollars go in every year. If your projection crosses a catch-up age (the year you turn 50, or the year you turn 64, when the higher limit for ages 60 through 63 ends), what goes in changes, and the calculator weights each year's deduction rate by what that year's dollars grow to.

Does the agency match go to Roth if I contribute Roth?

No. TSP states it plainly: "Agency or service contributions always go into your traditional balance, regardless of your contribution choice." That covers both the Agency Automatic 1 percent and the matching contributions. Your Roth contributions earn the same match as traditional ones, because the match is figured each pay period on how much you put in that period, up to 5 percent of that period's basic pay, not on which balance it goes to. It just lands on the traditional side and gets taxed when you withdraw it. Because that is true under either election, the match does not change the Roth versus traditional answer as long as the same dollars go in. If you switch to Roth and cut your contribution to keep your take-home pay the same, the match falls with the dollars, and the result headline says when that lost match outweighs the Roth advantage. All of this applies to FERS employees and to uniformed members under the Blended Retirement System. CSRS employees get no agency contributions at all (5 U.S.C. 8351(b)(3)), and neither do uniformed members under the legacy retired pay system, since 5 U.S.C. 8440e(e) pays service contributions only to BRS members. What can cost you match is putting in so much early that you reach the annual limit before the last pay period: TSP stops your contributions and the match stops with them, and this calculator shows the dollars lost.

What is the 2026 TSP contribution limit?

IRS Notice 2025-67 set the 2026 elective deferral limit under section 402(g) at $24,500, up from $23,500. The age 50 catch-up is $8,000, and the higher catch-up for anyone who is 60, 61, 62 or 63 during 2026 stays at $11,250. That puts the ceiling at $24,500 under age 50, $32,500 at 50 through 59 and 64 and over, and $35,750 at ages 60 through 63. TSP takes a single contribution election: everything you put in counts toward the $24,500 first, and only dollars above $24,500 count as catch-up. Agency contributions sit outside the 402(g) limit.

Who has to make Roth catch-up contributions in 2026?

Section 603 of the SECURE 2.0 Act, now at 26 U.S.C. 414(v)(7), requires catch-up contributions to be Roth for any participant whose prior calendar year Social Security wages from the employer sponsoring the plan exceeded an indexed threshold. IRS Notice 2025-67 set that threshold at $150,000 of 2025 wages for the 2026 contribution year, measured against W-2 box 3. TSP has confirmed it applies the rule from January 1, 2026. The rule reaches catch-up dollars only, which in the TSP means dollars above the $24,500 regular limit, so someone above the threshold who contributes $24,500 or less a year can still make all of it traditional. If you were at or below $150,000 in 2025, your catch-up election is still yours to make.

Why does Roth cost more take-home pay for the same contribution?

A traditional contribution comes out before federal income tax, so a $5,000 contribution in the 22 percent bracket only reduces your paycheck by $3,900. A Roth contribution of the same $5,000 reduces it by the full $5,000, because the tax is already paid. That is why this calculator shows two framings. Same dollars into the TSP means Roth shelters more real money but costs more take-home today. Same take-home pay means the Roth contribution is smaller, and the comparison becomes a clean bet on tax rates.

When are Roth TSP earnings tax free?

Your own Roth contributions always come out tax free. The earnings on them are tax free only in a qualified distribution, which TSP describes as requiring both conditions: five years have passed since January 1 of the calendar year of your first Roth TSP contribution, and you are at least 59 and a half, permanently disabled, or deceased. The five year clock starts on January 1 of that first contribution year, not on the contribution date, which means a December contribution buys you almost a free year on the clock.

What marginal rate should I use for retirement?

Add up what you expect to be taxable: your FERS annuity, the taxable share of Social Security, any TSP withdrawals from the traditional side, and other income, then find the bracket that total less your standard deduction falls in. Remember that your FERS annuity alone often fills the lower brackets, so the first dollar of a traditional TSP withdrawal is usually taxed at your top rate, not your average rate. If you expect to be in a 22 percent bracket in retirement and your deduction only saves 12 percent today, Roth is the better bet.

Does being 65 or older change the answer?

It can. At 65 the standard deduction grows by $2,050 for a single or head-of-household filer, or $1,650 for each spouse 65 or older on a joint return (26 U.S.C. 63(f); IRS Rev. Proc. 2025-32). On top of that, for tax years 2025 through 2028 only, there is a $6,000 senior deduction for each person 65 or older, which shrinks by 6 percent of modified adjusted gross income over $75,000 ($150,000 joint) and is not allowed on a married-filing-separately return (26 U.S.C. 151(d)(5)(C): "In the case of a taxable year beginning before January 1, 2029, there shall be allowed a deduction in an amount equal to $6,000 for each qualified individual"). Both lower your taxable income, so the traditional deduction can save a lower rate. A single filer at $75,000 who contributes 10 percent at 66 saves only 12.6 percent instead of 22 percent, which makes Roth the better choice at a 15 percent retirement rate. The calculator applies both for your age and, on a joint return, for a spouse 65 or older, and drops the senior deduction from 2029 in the projection. Enter your age on December 31: the IRS treats you as 65 on the day before your 65th birthday, so if you turn 65 on January 1 of next year, enter 65.

Can I split my contributions between Roth and traditional?

Yes. TSP lets you direct any share of your own contributions to either balance, and you can change the split at any time through your payroll system. Splitting is a reasonable answer when you genuinely do not know which direction rates will move, and it is the only answer if you want some tax-free income to draw on in a year when a large withdrawal would push you into a higher bracket or across an IRMAA line.

Calculator

Roth vs Traditional TSP

One number decides this: the retirement tax rate at which Roth starts beating traditional. This tool finds it from the 2026 IRS brackets, then shows the after-tax result both ways, because Roth costs more take-home pay today for the same contribution.

Reviewed by Jonathan D., 20-year federal employee · Formulas verified against IRS.gov and TSP.gov · Updated October 2026

Rule snapshot

Reviewed October 3, 2026. Sources: IRS Notice 2025-67 (2026 limits) · IRS Rev. Proc. 2025-32 (2026 brackets) · TSP: traditional and Roth contributions · TSP: Summary of the TSP (catch-up spillover, the match) · 5 U.S.C. 8432(c) (match per pay period) · 5 CFR 892.102 (FEHB premium conversion) · 5 U.S.C. 8351(b)(3) (no agency contributions for CSRS) · 5 U.S.C. 8440e(e) (BRS service contributions) · 26 U.S.C. 151(d)(5)(C) (senior deduction, 2025 to 2028) · 26 U.S.C. 63(f) (additional standard deduction at 65) · 26 U.S.C. 402A. Your inputs stay in your browser. Nothing is sent to a server and nothing is saved.

Your pay and your election

Annual basic payBasic pay including locality. Not awards or overtime.

Your contribution, percent of pay5 percent draws the full agency match.

Retirement systemDecides whether agency money exists. CSRS and legacy uniformed members get none.

Filing statusSets the 2026 bracket table used for your current rate.

Other household taxable incomeSpouse pay, interest, rent. Leave at 0 if none.

Pre-tax payroll deductions, per yearYour share of FEHB and FEDVIP premiums (paid pre-tax under premium conversion) plus any FSAFEDS election. Lowers taxable income, not basic pay. Leave at 0 if none.

Retirement assumptions

Your age this yearAge on December 31. Drives catch-up eligibility and, at 65 or older, the extra standard deduction and the 2025-2028 senior deduction. The IRS counts you as 65 the day before your 65th birthday, so if you turn 65 on January 1, enter 65.

Years until you start withdrawing

Expected annual return, percentNominal, before inflation. Same rate is used on both sides.

Marginal tax rate you expect in retirement, percentCount your FERS annuity, the taxable part of Social Security and traditional TSP withdrawals.

Extra dollars and catch-up

Extra dollars a year on top of your percentTSP takes one election. Your percent plus these dollars fill the $24,500 regular limit first; only dollars above $24,500 count as catch-up (age 50 and over, up to $8,000, or $11,250 if you are 60 through 63 this year).

2025 Social Security wages (W-2 box 3)Above $150,000 and any dollars past $24,500 (your catch-up) must be Roth in 2026.

Traditional wins on these numbers once agency money is counted. On your own contributions alone the two end less than a dollar apart: your retirement rate is 22.0 percent and the deduction saves you 22.0 percent now. But holding take-home steady puts only $3,900 a year into Roth, which draws $550 a year less match. Counting the lost match, traditional comes out $16,518 ahead. Break-even retirement tax rate 22 percent.

Break-even retirement tax rate

22.00%

Pay more than this in retirement and Roth wins. Pay less and traditional wins.

Same take-home pay today

Same take-home pay today: contributions, take-home cost, and after-tax value at retirement
Measure	Traditional	Roth
Contributed per year	$5,000	$3,900
Take-home given up per year	$3,900	$3,900
Balance at retirement	$192,517	$150,163
After tax, yours to spend	$150,163	$150,163

Holding your paycheck steady, Roth and traditional end in the same place after tax because your retirement rate matches the 22.0 percent the deduction saves you now.

Same dollars into the TSP

Same dollars into the TSP: contributions, take-home cost, and after-tax value at retirement
Measure	Traditional	Roth
Contributed per year	$5,000	$5,000
Take-home given up per year	$3,900	$5,000
Balance at retirement	$192,517	$192,517
After tax, yours to spend	$150,163	$192,517

Putting the same $5,000 a year into Roth leaves $42,354 more after tax, because the Roth dollars are already taxed. It costs $1,100 more take-home pay each year.

Agency money is traditional either way. Your agency puts $5,000 a year in (5.0 percent of pay: $1,000 automatic plus $4,000 matching, figured each of the 26 pay periods). It goes to the traditional balance even for a Roth contributor, grows to $192,517, and is taxed at withdrawal in both scenarios. For the same dollars it does not change the answer. Holding take-home steady does: the Roth side puts in less and draws $550 a year less match.

How we got this

Taxable income before any TSP deduction: $100,000 income minus the $16,100 standard deduction = $83,900. That lands in the 22 percent bracket (IRS Rev. Proc. 2025-32).
Your election: $5,000 a year. The first $24,500 is a regular contribution; only dollars above that count as catch-up.
Your $5,000 traditional contribution cuts your 2026 federal income tax by $1,100, which is 22.00 percent of the deductible amount.
Employee balance after 20 years at 6 percent nominal, one twelfth contributed each month: $192,517.
Taxed at 22 percent it is worth $150,163.
Same dollars in Roth: $192,517, all of it yours. Extra take-home cost: $1,100 a year.
Same take-home instead: $3,900 a year into Roth grows to $150,163, all of it yours.
Break-even retirement rate is 22.00 percent. Above that, Roth wins. Below it, traditional wins. Years and return do not move this number because they scale both sides equally.
Agency money (5.0 percent of pay, $5,000 a year: $1,000 automatic plus $4,000 matching) is traditional either way and grows to $192,517. The match is figured each of the 26 pay periods on what you put in that period, whichever balance it goes to, so it is the same under both elections for the same dollars. It is taxed at withdrawal in both scenarios, so it does not change the choice.

In the same take-home comparison the Roth side puts in $3,900 a year instead of $5,000. The match follows the dollars each pay period, so at that level it would be $3,450 rather than $4,000, $550 a year less. Both comparisons above leave agency money out of the verdict; if you go Roth, keep at least 5 percent of pay going in every pay period to hold the full match.

No pre-tax payroll deductions were entered. Most federal employees pay FEHB premiums pre-tax under premium conversion (5 CFR 892.102), and FEDVIP premiums and FSAFEDS elections also come off taxable wages. Enter them so the deduction is figured on your real taxable income; near a bracket line they can move the break-even rate.

Roth earnings come out tax free only if the withdrawal is qualified: five years since January 1 of the year of your first Roth TSP contribution, and age 59 and a half, disability, or death (26 U.S.C. 402A(d)(2)).

The projection holds the 2026 brackets, the 2026 standard deduction (and its age 65 addition) and the 2026 contribution limits ($24,500 elective deferral, $8,000 catch-up, $11,250 higher catch-up) flat in dollars for every year. All of them are indexed in real life, so a long projection is a comparison of today's rates, not a forecast. Which catch-up limit applies does change with your age each year: none before the year you turn 50, the higher limit only in the years you turn 60 through 63, and the regular catch-up limit again from the year you turn 64 (26 U.S.C. 414(v)(2)(E); IRS Notice 2025-67; TSP Summary of the TSP).

Your pay, your contribution percent and the return are held flat too, and no state or local income tax is modeled. Several states exempt some retirement income, which can move the break-even rate by several points.

Balances assume one twelfth of the annual contribution lands at the end of each month and compounds at one twelfth of the 6 percent nominal return. All dollar figures are nominal future dollars, not inflation-adjusted.

What this models, and what it does not

Scope of the Roth versus traditional TSP calculator: what the engine accounts for and the limits you should know before acting on the result
Modeled	Not modeled
2026 federal income tax brackets and standard deduction for all four filing statuses, from IRS Rev. Proc. 2025-32, applied after any pre-tax payroll deductions you enter (FEHB and FEDVIP premiums under premium conversion, FSAFEDS). At 65 and over, the additional standard deduction (26 U.S.C. 63(f): $2,050 unmarried, $1,650 per spouse) and the $6,000 senior deduction with its 6 percent phase-out over $75,000 or $150,000 of MAGI (26 U.S.C. 151(d)(5)(C)), figured with and without the traditional contribution because it lowers MAGI. The senior deduction is scheduled only for tax years 2025 through 2028, so the projection drops it from 2029.	State and local income tax. Several states exempt some retirement income, which can move the break-even by several points.
The blended rate your traditional contribution actually saves, including the case where the contribution crosses a bracket line.	Itemized deductions, credits, the qualified business income deduction, and the extra deduction for blindness. A spouse who turns 65 during the projection (a spouse under 65 in 2026 is treated as under 65 throughout), the senior deduction on a separate return for a spouse with no income, and the Social Security number requirement for the senior deduction (151(d)(5)(C)(iv)). Pre-tax payroll deductions count only if you enter them.
The 2026 elective deferral limit of $24,500 plus the $8,000 and $11,250 catch-up limits. Your percent and any extra dollars are one election: the first $24,500 is regular and only the excess is catch-up, as TSP applies it. Each projection year uses the catch-up limit for the age you turn that year: none before 50, $11,250 only in the years you turn 60 through 63, and $8,000 again from the year you turn 64 (26 U.S.C. 414(v)(2)(E); TSPBK08). The section 415(c) annual additions limit of $72,000 on employee plus agency dollars, catch-up excluded, which 5 U.S.C. 8432(d) applies to the TSP; at the $400,000 basic pay this page accepts it never binds for a civilian.	Future inflation indexing of the limits: the 2026 dollar amounts are held for every projection year. The 415(c)(1)(B) leg (100 percent of pay), which only an election near 100 percent could reach; the form refuses an election that payroll taxes and the retirement deduction leave no room for. The section 401(a)(17) compensation limit ($360,000 in 2026): 5 U.S.C. 8432 sets agency money as a percent of basic pay and limits it only through section 415, so the tool does not apply it.
The SECURE 2.0 section 603 test and its arithmetic: above $150,000 of prior-year Social Security wages, dollars above the $24,500 regular limit are Roth under both elections, so the deduction, the take-home cost and the break-even rate are figured on the first $24,500. Below $24,500 the rule has nothing to reach.	Combat-zone tax-exempt pay, where TSP requires Roth catch-up regardless of income.
Agency automatic 1 percent and matching dollars for FERS employees and Blended Retirement System members, always traditional, figured each of 26 pay periods: the match you forfeit by contributing under 5 percent, the match you lose when contributions reach the annual limit early and stop, and the match the Roth side loses when it holds take-home steady. CSRS employees (5 U.S.C. 8351(b)(3)) and legacy uniformed members (5 U.S.C. 8440e(e) covers BRS only) get $0 of agency money.	Mid-year pay raises, step increases, promotions, and any year when you change your contribution percent. For BRS, the 60-day wait for the automatic 1 percent, the 2 years and 1 day wait for the match, and the stop at 26 years of service (8440e(e)(3)); the tool assumes you are inside both windows.
A single flat nominal return applied to both elections, with one twelfth of the annual contribution landing at the end of each month and compounding at one twelfth of the stated rate.	Market sequence risk, fund expense differences, and inflation. All figures are nominal future dollars.
A single flat retirement marginal rate on the traditional balance.	Bracket changes over time, IRMAA surcharges, the taxable share of Social Security, and required minimum distributions forcing income you did not want.

Precision limit: contributions are timed monthly, not annually, because the timing convention is worth real money rather than rounding error. On the example below, $5,000 a year for 20 years at 6 percent is $192,517 with monthly contributions and $183,928 if the whole year lands in December, a gap of $8,589 or 4.67 percent. Federal payroll actually runs 26 pay periods, which on the same example comes to $192,961, about $444 or 0.23 percent above the monthly figure this tool reports. The break-even rate at the top of the page does not move with the timing convention either way, because the convention scales both elections equally. This is an estimate, not tax advice. Talk to a tax professional before changing a large election.

The only thing that decides this

Traditional TSP skips the tax now and pays it later. Roth TSP pays the tax now and skips it later. Hold your paycheck steady and the whole question collapses to a rate comparison: whichever rate is lower is the one you want to pay. The break-even figure at the top of this page is the rate your traditional deduction actually saves you in 2026. Expect a higher rate in retirement and Roth is the better bet. Expect a lower one and traditional is.

Notice what is missing from that: your return assumption and your years to retirement. Both scale the Roth side and the traditional side by the same factor, so they cancel. Change the return from 5 percent to 9 percent in the tool and watch the break-even rate hold still. A long horizon does not favor Roth on its own. The one exception is a projection that crosses a catch-up age, such as turning 64 when the higher limit for ages 60 through 63 ends: the dollars going in change, and so can the rate the deduction saves.

Why we show two framings

Contribute $5,000 traditional in the 22 percent bracket and your paycheck drops by $3,900, because the deduction hands $1,100 back. Contribute $5,000 Roth and your paycheck drops by the full $5,000. Those are not the same decision, so comparing them as if they were loads the answer toward Roth.

The same take-home panel keeps your paycheck fixed and shrinks the Roth contribution to match, which isolates the rate bet. The same dollars panel keeps the contribution fixed and shows what Roth really buys you: more sheltered money, at a real cost to this month's budget. If you are already contributing the full $24,500 limit, the second framing is the one that matters, because $24,500 of Roth money is worth more at retirement than $24,500 of traditional money and the limit will not let you make up the difference.

The match drops out only when the dollars stay the same

Agency money is always traditional. TSP puts it in one sentence: agency or service contributions always go into your traditional balance, regardless of your contribution choice. The match is figured each pay period on what you put in that period, so the same dollars earn the same match whether they go Roth or traditional. Since that is true under either election, it drops out of the same dollars comparison.

It does not drop out of the same take-home comparison. Holding your paycheck steady means putting fewer dollars into Roth, $3,900 instead of $5,000 in the example above, and the match follows the dollars: 3.9 percent of pay draws a 3.45 percent match instead of 4 percent, $550 a year less on a $100,000 salary. Whenever the Roth side loses match, the result headline counts it and names the winner after the lost match. CSRS employees and uniformed members under the legacy retired pay system get no agency money, so none of this applies to them.

What does matter is whether you are capturing the match at all. Five percent of basic pay draws the full 4 percent match plus the 1 percent automatic contribution. Anything under 5 percent leaves money behind, and the tool prints the annual figure you are forfeiting. Fix that before you spend another minute on the Roth question. The other way to lose match is the reverse: contribute so much that you reach the annual limit before the last pay period, and your contributions stop along with the match for the rest of the year. The tool flags the pay period and the dollars when that happens. Our TSP Contribution Calculator works out the per-pay-period figure.

If you are 50 or older in 2026

Part of this choice may already be made for you. Section 603 of the SECURE 2.0 Act requires catch-up contributions to be Roth when your prior-year Social Security wages from your federal employer exceeded an indexed threshold. IRS Notice 2025-67 set that threshold at $150,000 of 2025 wages, and TSP applies the rule from January 1, 2026. TSP takes one election, and your dollars become catch-up only after they pass the $24,500 regular limit. Above the wage line, that excess, up to $8,000 or $11,250, has to go Roth. Your first $24,500 is still your call, and if you put in $24,500 or less the rule does not touch you. Enter your 2025 wages above the threshold and the tool deducts only that $24,500, which is the point most calculators miss: a 61-year-old contributing the full $35,750 does not get a $35,750 deduction. For a single filer on $160,000 of basic pay that drops the first-year tax saving from $8,580 to $5,880, and the Roth catch-up shows up as after-tax money on both sides of the comparison. Details in our guide to the mandatory Roth catch-up.