Roth TSP vs. traditional TSP is closer than it looks once retired pay fills your low brackets, and First Premier Bank treats the rate your surviving spouse will pay as the deciding number. For illustration, a $24,500 traditional deferral at a 12% rate saves $2,940 this year, but if a widowed spouse later draws that $24,500 as a single filer at 22%, the tax cost is $5,390.
The decision shows up in a small place: a payroll election form at your Guard, Reserve or federal civilian job, or the TSP website's contribution screen. You tick traditional because you always have. At First Premier Bank, we run the split for a pension household one test at a time, with your 1099-Rs on the table, before anyone changes a percentage. This article works through those tests in order.
By Hiroshi Tanaka, CFP — Retirement Planning Specialist | Reviewed by Marcus Thompson, CFAHiroshi builds retirement income plans using the bucket strategy, coordinating taxable, tax-deferred, and tax-free accounts.
A $24,500 deferral saves $2,940 at 12%, but costs $5,390 if the survivor draws it single at 22%. Price both ends before you tick the box.
Dana Whitfield, CPA and Tax Director at First Premier Bank
At 64 the catch-up is $8,000, not $11,250. Check that your payroll election matches the right age, because the extra $3,250 doesn't go in on its own.
Marcus Hale, CFP® and Lead Advisor at First Premier Bank
Step 1: Stack the income that's already taxed
Start by laying out every dollar that arrives whether or not you defer anything. Gather the DFAS 1099-R for retired pay, the 1099-R for a spouse's pension, the W-2 from the part-time or civilian job and both SSA benefit statements. Leave VA disability compensation off the pile; it isn't taxable, and counting it makes your bracket look higher than it is.
Then decide one thing. Does retired pay plus the spouse's pension already cover the $32,200 standard deduction for married filing jointly in 2026? If it does, the first dollar of your TSP deferral doesn't come out of a zero bracket. It comes out of a taxed one, so traditional saves only your marginal rate, often 12%, and not the full amount people imagine. Retired pay is a lot like a floor that's already been laid; new deferrals stack on top of it.
People often forget Social Security here. Once benefits start, up to 85% of them can become taxable. If you claim in the same year you change a deferral choice, that can lift the marginal rate you're comparing against. So put both SSA benefit amounts into the stack beside wages and pension before you compare rates.
What to gather and what to decide
The slip people make at this step
Step 2: Can I still use the bigger catch-up at 64?
No. For 2026 the IRS allows the $11,250 catch-up only at ages 60 to 63, so at 64 it drops back to $8,000, for a $32,500 total in the TSP. The Roth-only catch-up rule applies only if prior-year FICA wages from that employer topped $150,000, which part-time pay of about $40K won't reach. The slip: leaving a payroll election sized for $11,250 in place and assuming the extra went in.
Step 3: Roth TSP vs. traditional TSP for the spouse who outlives you
Hypothetical: Tomasz, 64, is a retired Air Force master sergeant working part-time in airport operations. Marta, 66, is a retired school secretary. His VA rating is 60%, and they hold $650K across the TSP and 2 IRAs. Tomasz defers $24,500. Retired pay and Marta's pension already pass the $32,200 standard deduction, so assume each deferred dollar sits at a 12% rate.
Traditional saves $24,500 × 12% = $2,940 this year. If Tomasz dies first and Marta later draws that $24,500 as a single filer at an assumed 22%, she pays $24,500 × 22% = $5,390. The household loses $5,390 − $2,940 = $2,450, before growth. If the money passes to their adult children at an assumed 24%, the tax cost is $5,880. Roth pays the $2,940 once, and qualified income draws after the 5-year rule are tax-free. Traditional shifts tax to a later year; it saves only when the later rate is lower. TSP funds rise and fall, and a balance can end up below what was contributed. The before-growth figures scale up or down with the account.
The survivor squeeze is the reason. Once the year Tomasz dies has passed, and with no dependent child at home, Marta files single. Most of the same pension and Social Security income then lands in narrower brackets. For your own household, read the right-hand column of the table. Then rerun the arithmetic with your own amounts in place of Tomasz and Marta's.
Heirs face their own clock. Most adult-child heirs must clear an inherited account within 10 years, often in their peak earning years. Roth TSP balances have no lifetime RMDs. Traditional balances face RMDs at 75 for anyone born in 1960 or later, which covers both Tomasz and Marta. For more on that rule see our survivor benefit and tax planning pages.
The worked numbers
Why the survivor and heirs change the answer
Decision rule: compare today's marginal rate with the rate your surviving spouse or heirs will likely pay. If theirs is the same or higher, a Roth deferral costs nothing extra and usually comes out ahead; traditional saves tax only when the later rate is lower.
| Common belief | What the rule says | What it means for you |
|---|---|---|
| Traditional always saves tax | Tax moves to the income-draw year | Saves only if the later rate is lower |
| Roth TSP has an income limit | No income limit on Roth TSP | Any earner can choose Roth |
| Catch-up at 64 is $11,250 | $11,250 only at ages 60-63 | Tomasz's catch-up is $8,000 |
| A widow keeps joint brackets | Single filing after the year of death | Same income, narrower brackets |
| Roth TSP forces RMDs | No lifetime RMDs on Roth balances | Roth side can sit untouched |
Step 4: Check your own accounts and question the plan
Run four checks against your statements, then ask three questions. Traditional still wins if you need the cash flow now or expect a lower rate later, such as a big income drop or a move to a state that doesn't tax retirement income. This article covers federal tax only, skips in-plan conversions and assumes your job offers TSP access.
Ask agency HR or payroll whether the Roth percentage applies to catch-up dollars separately, and when a new election takes effect. Ask the TSP how the quarterly statement splits traditional and Roth balances. If payroll can't confirm whether past deferrals went Roth or traditional, that answer should worry you; get it in writing before changing anything.
Keeping every deferral traditional out of a 30-year 'deduct now' habit is a careful saver's mistake. At $32,500 a year for 3 years, $97,500 goes traditional at an assumed 12%; drawn single at 22%, the extra 10 points cost $9,750 before growth. Counting VA pay as taxable income overstates the bracket and pushes toward traditional. And assuming the $8,000 catch-up at 64 leaves $16,500 of planned deferral unmade ($24,500 − $8,000).
The table sets the two accounts side by side on five points the IRS rules actually decide.
The four-point account check
Questions for HR and the TSP
| Point | Roth TSP | Traditional TSP |
|---|---|---|
| Tax this year | $2,940 paid now | $2,940 saved now |
| Tax at income draw | Qualified draws tax-free | $5,390 if Marta draws single |
| Tax if heirs inherit | None on qualified draws | $5,880 at 24% |
| Lifetime RMDs | None on Roth balances | Start at 75 if born 1960+ |
| Income limit | None on Roth TSP | None on traditional |
- Retired pay vs. deduction: does it already cover $32,200 for 2026?
- Survivor's filing status: would most income stay if one of you died?
- Roth 5-year clock: when did the first Roth TSP dollar go in?
- Beneficiary form: is the TSP-3 current, and does it name the spouse first?
Your deferral split, priced at First Premier Bank
First Premier Bank puts the next due date first (the payroll election, Part B enrollment, the Social Security claim). We then price the Roth and traditional split for the survivor with your 1099-Rs on the table. We tell you the fee when we first talk and put it in a written agreement before any work starts. The request form is the way in.
Traditional shifts tax to a later year; it saves only when the later rate is lower.
What people ask about Roth TSP vs. traditional TSP
Can I change my Roth TSP election next month if our Social Security start date moves?
I'm 64 and work part-time at an airfield; should my $8,000 catch-up go Roth or traditional?
Will Mom owe more tax on Dad's traditional TSP if he dies first?
How much does a $24,500 traditional TSP deferral save in a 12% bracket?
Read the rules at the source
This is general information and education, not individual investment, tax, or legal advice. Investing involves risk, including loss of principal. Before making any financial decision, talk to a qualified professional about your specific circumstances.