Enter your grade, time in service, and combat zone months. The calculator builds your taxable income from the 2026 pay tables, then shows how much you could convert from traditional TSP to Roth before crossing into the next federal bracket, and what it would cost.
Creditable years, as shown on your LES.
Months with at least one day in a combat zone. Enlisted and warrant officers: all basic pay excluded. Commissioned officers: excluded up to $11,391.90/month.
Spouse wages, interest, side income. Not BAH or BAS (those are tax-free).
Pre-tax contributions made in non-CZTE months. These reduce your taxable income. Roth contributions don't go here.
$2,200 child tax credit each in 2026.
Your total TSP balance minus your Roth balance. Include agency contributions (Auto 1% and Match) — they are always traditional.
From the "Nontaxable Balances" section of your TSP account: use the "Nontaxable Contributions" line (combat zone money), NOT the Roth Contributions line. If you never deployed, leave this at 0.
$40,000
Taxable portion of conversion
$0
Tax-free portion moved
$0
Added federal tax
$0
Effective rate on conversion
0%
Baseline taxable incomeTaxable portion of conversionUnused bracket room
Educational tool only, not tax or investment advice. Basic pay from the 2026 DFAS pay tables (3.8% raise, effective January 1, 2026); O-6 and below capped at Executive Schedule Level V. Assumes the standard deduction, 2026 federal ordinary income brackets, and a $2,200-per-child tax credit with no phase-out modeling (phase-outs begin at $400k AGI joint / $200k single). CZTE math: full exclusion for enlisted and warrant officers, $11,391.90/month exclusion cap for commissioned officers, $225/month hostile fire pay included in combat zone months. Ignores special pays, bonuses, and state income tax, all of which can change the result. TSP in-plan conversions are irreversible, prorated between pre-tax and tax-exempt money, have no tax withholding (plan for estimated payments), and start a five-year clock. Talk to a tax professional before converting.
Pay tax when you'll pay the least tax.
Military servicemembers have a unique opportunity when they are on a combat zone military deployment that lowers their taxable income for the year. They might move from the 22% bracket to the 0% bracket for one or two years and back to a higher bracket the following year.
This means that if you have money in the Traditional side of your Thrift Savings Plan (TSP), you could move it over to your Roth side, pay taxes in a very low tax bracket, and lock in tax-free growth and tax-free withdrawals after age 59.5. A tremendous opportunity, especially if you're expecting a military pension, which is all taxable income (unless offset by a VA disability rating).
Please note that you'll need to pay the tax on the conversion with money outside of the TSP. Have that money saved up and ready to pay when you file your taxes.
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