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Best after-tax cash yields in Montana
Updated Oct 16, 2026 · By Jeison Cobb
Data as of 2026-10-16 12:30 ET · Montana state tax 5.65% · federal bracket 22%
| # | Account | Yield | After-tax | $ / yr after tax |
|---|---|---|---|---|
| 1 | US T-Bill 52 Weeks US Treasury-backedstate-tax free | 4.47% | 3.49% | $349 |
| 2 | US T-Bill 26 Weeks US Treasury-backedstate-tax free | 4.36% | 3.40% | $340 |
| 3 | US T-Bill 13 Weeks US Treasury-backedstate-tax free | 4.20% | 3.28% | $328 |
| 4 | Marcus High-Yield CD (12-mo) Member FDIC | 4.40% | 3.24% | $324 |
| 5 | US T-Bill 4 Weeks US Treasury-backedstate-tax free | 4.07% | 3.17% | $317 |
| 6 | Ally High Yield CD (12-mo) Member FDIC | 4.30% | 3.16% | $316 |
| 7 | SoFi Checking & Savings Member FDIC | 4.20% | 3.09% | $309 |
| 8 | LendingClub LevelUp Savings Member FDIC | 4.20% | 3.09% | $309 |
| 9 | VUSXX (Vanguard Treasury MMF) Fund · not FDIC insuredstate-tax free | 3.88% | 3.03% | $303 |
| 10 | Bread Savings HYSA Member FDIC | 4.05% | 2.98% | $298 |
Min to open / monthly fee come from each provider's own page (see "terms" link); "—" means we couldn't confirm it, so we don't guess. Different federal bracket? Use the full ranking tool.
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How Montana taxes your cash
Montana's top state income tax rate is 5.65%. Interest from savings accounts, CDs and most money market funds is taxed by Montana. Interest from US Treasuries (T-bills, T-bill ETFs like SGOV/BIL, and Treasury money funds) is exempt from state tax by federal law. To match a 4.47% Treasury after tax, a bank account in Montana needs about 4.74% APY.
Right now in Montana, the best Treasury option (US T-Bill 52 Weeks, 3.49% after tax) beats the best bank option (Marcus High-Yield CD (12-mo), 3.24% after tax), assuming a 22% federal bracket.
FAQ
What is the best after-tax place for cash in Montana?
As of 2026-10-16, the top after-tax yield for a 22% federal bracket in Montana is US T-Bill 52 Weeks at 3.49% (4.47% before tax).
Are T-bills taxed in Montana?
No. Interest on US Treasury bills is exempt from state and local income tax, including Montana's income tax. It is still subject to federal income tax.
What is Montana's state income tax rate on interest?
We use Montana's top marginal rate of 5.65% (Tax Foundation, 2026). Your actual rate may be lower depending on income.
How is after-tax yield calculated?
Bank interest: yield × (1 − federal rate) × (1 − state rate). Treasuries: yield × (1 − federal rate). We assume a 22% federal bracket on this page; use the home page tool to change it.
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Other states
Method: bank = yield × (1 − federal) × (1 − state); Treasuries = yield × (1 − federal). Uses the state's top marginal rate (Tax Foundation 2026); ignores local tax and partial-exemption rules for government MMFs. Not financial advice. Back to CashYield home.