Where to Stash Your Cash v11

Where to Stash Your Cash?

Cash deposit

Taxable income

Filing status

State

Rates as of September 29, 2026: bank savings APYs as posted September 28–29, 2026; money-market fund 7-day SEC yields as of September 28, 2026 (Schwab funds September 25, 2026). Rates change daily.

Marginal tax rates on interest income

Federal	—
NIIT	—
State	—
Local	—
Total	—

What gets taxed and what doesn't

Bank savings accounts are fully taxed at ordinary income tax rates at the federal, state and local levels.
Municipal bond money markets are generally exempt from regular federal income tax; a single-state fund may also be exempt from that state's taxes for resident investors, depending on fund holdings and state rules.
Direct Treasury bills are taxed at the federal level but exempt from state and local taxes; Treasury money-market funds pass through state-exempt income based on their holdings and annual tax reporting.

This calculator is for educational purposes only and is not tax, legal, or investment advice. Results are simplified estimates based on the inputs and assumptions shown — including treating taxable income as a MAGI proxy measured before the interest modeled here, and treating Treasury money-market funds that hold mostly Treasuries as fully state-exempt and those that hold mostly repurchase agreements as fully state-taxable. Tax data reflects the 2026 tax year (California, Idaho and Vermont: 2025 brackets). Consult a qualified professional before making tax or investment decisions.

Light Dark

What this calculator is for

Four ordinary places to hold cash pay very different amounts, and the tax code treats each one differently. This compares what each pays before tax with what you actually keep after federal, state and local tax — because the ranking depends on where you live and what you earn, not just on the advertised yield.

How the calculation works

Your taxable income and filing status set a marginal federal rate, and the 3.8% net investment income tax is added above $250,000 married filing jointly, $200,000 single or head of household, or $125,000 married filing separately.
Your state contributes a marginal rate from its own bracket table. Five states add a local rate; New York City and Maryland's Anne Arundel County are taken from their own brackets, Yonkers is computed as 16.75% of your New York State liability, and Portland adds Multnomah County's Preschool for All tax (1.5%, rising to 3%) and Metro's Supportive Housing Services tax (1%) above their own thresholds.
Each vehicle's yield is applied to your deposit to give pre-tax interest, then taxed according to its own treatment: bank interest at the full combined rate, Treasury money-market income at the federal rate plus the net investment income tax only (or at the full combined rate for a fund that holds mostly repurchase agreements), and municipal money-market income at state and local rates only — or at nothing at all for a single-state fund matching your state.
The municipal row selects whichever available fund leaves you the most after tax, which is not always the single-state one.

Where the figures come from

Federal brackets and the net investment income tax thresholds are for the 2026 tax year. State rates are each state's 2026 schedules, built on the Tax Foundation's 2026 tables and revised on 29 September 2026 for laws enacted during 2026 in Arkansas, South Carolina, Utah and West Virginia; Georgia is at 4.99% under House Bill 463. California, Idaho and Vermont are still on their 2025 brackets, because their 2026 schedules were not published when the tables were compiled. Local rates are for 2026: Maryland's from the Comptroller's 2026 county list, and Portland's Metro threshold is the 2026 inflation-indexed figure. Bank rates were posted on 28–29 September 2026 and fund seven-day yields are as of 28 September 2026 (Schwab 25 September), after the Federal Reserve raised its target range to 3.75–4.00% on 16 September. They change daily, and municipal fund yields are near their usual quarter-end peak. High-yield savings rates are the permanent rates, not introductory promotions.

Which assumptions do the most work

The yield gap between vehicles sets the size of the answer — the spread from a branch savings account to a Treasury fund is several hundredfold, and it dwarfs every tax effect. Your combined state and local rate then decides the order: it is what makes a Treasury fund's state exemption worth more or less than a municipal fund's federal exemption. Your deposit scales all four bars equally and never changes the ranking. At the yields shown, the winner depends on your bracket: at lower federal rates a Treasury fund usually keeps the most, while at the top federal rates a municipal fund — especially a single-state fund in a high-tax state — now keeps more.

What it does not model

A single marginal rate is applied to the whole of the interest, so on a large deposit whose interest spans more than one bracket the after-tax figures are optimistic.
Taxable income stands in for modified adjusted gross income, and the net investment income tax threshold is tested before the modelled interest is added — so a household just below a threshold is shown no such tax when a little would in fact apply.
Each Treasury money-market fund is treated as either wholly state-exempt (close to 100% Treasuries) or wholly state-taxable (substantial repurchase agreements). Real funds sit in between, and each fund's annual tax statement is the authority.
One state of residence for a whole year; no alternative minimum tax on private-activity municipal bonds; no bank promotional or tiered rates; no qualifying-surviving-spouse status; Portland is modelled as the Multnomah County part of the city, and its flat arts tax is left out because it is not a rate on interest.

This is a hypothetical illustration for education, not a quote, a projection of any individual result, or tax advice.