HYSA Tax Rate: How High-Yield Savings Interest Is Taxed in 2026

By Kevin Luu, Co-Founder and Chief Learning Officer. Reviewed on 2026-09-30.

There is no special HYSA tax rate. Interest from a high-yield savings account is taxed as ordinary income at your top marginal rate, the same as your salary, and it is taxable in the year the bank credits it, whether or not you withdraw it. For a two-income family earning $900,000 in California, that typically means about 51 cents of every interest dollar goes to federal and state tax in 2026, so a 4% account keeps a little under 2% after tax.

Below is the math at your income level, how California and Washington differ, and the one decision worth making about where your cash sits.

How HYSA interest is taxed in 2026

The IRS lists interest on bank accounts, money market accounts and CDs as taxable interest (IRS Topic 403). Three rules matter:

• Ordinary income. Interest is stacked on top of your wages and RSU income and taxed at your highest bracket. It never gets the lower long-term capital gains rates.
• Net Investment Income Tax. Interest counts as investment income. Married couples filing jointly with modified AGI over $250,000 pay an extra 3.8% on their net investment income, or on the amount their modified AGI exceeds $250,000 if that is smaller (IRS NIIT page). That threshold is not indexed, so almost every family reading this pays it.
• Taxed when credited. Interest that is credited and available to withdraw is taxable that year, even if you leave it in the account (IRS Publication 550).

Your bank sends Form 1099-INT if it paid you $10 or more. You still owe tax on smaller amounts; the IRS requires you to report all taxable interest whether or not a form arrives (IRS Topic 403). Families with accounts at three or four online banks should collect every 1099-INT before sending documents to their preparer, because a missed form is a common source of IRS notices.

Your federal rate at $600,000 to $1.2 million of household income

For 2026, the federal brackets for married couples filing jointly are 10%, 12%, 22%, 24%, 32%, 35% and 37%. The 35% bracket runs from $512,450 to $768,700 of taxable income, and 37% applies above $768,700 (IRS Rev. Proc. 2025-32). Add the 3.8% NIIT and the federal rate on interest looks like this:

A household with $650,000 of wages usually lands in the 35% bracket after 401(k) deferrals and the $32,200 standard deduction. At $900,000 and above, most families are in the 37% bracket.

California versus Washington: what the state adds

California taxes interest as ordinary income at the same rates as wages. FTB has not yet published 2026 brackets, so the 2025 schedule is the latest guide: for joint filers, 9.3% up to $742,958 of taxable income, 10.3% up to $891,542, 11.3% up to $1,485,906, and 12.3% above that (FTB 2025 rate schedules). A 1% Behavioral Health Services Tax applies to taxable income over $1,000,000, which is how the top rate reaches 13.3% (FTB Form 540 booklet).

The state tax is not offset federally for most readers. The 2026 SALT deduction cap is $40,400, but it phases down to $10,000 once modified AGI passes roughly $606,333 for joint filers (P.L. 119-21). Your property tax alone usually fills that $10,000, so each extra dollar of California tax on interest is a full cost.

Washington has no individual income tax in 2026 (WA DOR), and the state capital gains tax does not reach bank interest. Two caveats for high earners: Washington’s new 9.9% income tax on AGI over $1,000,000 starts January 1, 2028, and DOR has not yet published how it will define income. A Seattle-area family near $1.2 million should plan for the possibility that interest is taxed by the state from 2028, depending on how DOR defines income (WA DOR income tax FAQ).

Worked example: a $300,000 emergency fund at 4%

Assumptions (illustrative, not a rate forecast): married filing jointly, two W-2 incomes plus RSUs totalling $900,000, both spouses defer $24,500 to their 401(k) for 2026, standard deduction, no other large deductions. Federal taxable income is about $818,800 ($900,000 minus $49,000 minus $32,200), which is in the 37% bracket. California taxable income is assumed at about $845,000, in the 10.3% bracket. The cash earns an assumed 4.00% APY, or $12,000 a year.

Push the same California family to $1.2 million with a large RSU vest and the state rate on the next dollar becomes 11.3% plus the 1% Behavioral Health Services Tax. Combined with 40.8% federal, that is 53.1%, and the $12,000 of interest keeps about $5,628.

None of this means a HYSA is a mistake. It means the after-tax yield, not the advertised APY, is the number to compare.

Where the tax is lower: Treasuries and state-exempt funds

Interest on Treasury bills, notes and bonds is taxed federally but is exempt from all state and local income tax (IRS Topic 403; 31 U.S.C. 3124). For a California family, that removes the 10.3% to 12.3% layer.

• Same example with Treasury bills. At the same assumed 4.00% yield, the $900,000 California family pays 40.8% instead of 51.1% and keeps $7,104 instead of $5,868, about $1,236 more a year on $300,000.
• Break-even yield. To match a 4.00% T-bill after tax, the HYSA has to pay about 4.84% (2.368% divided by 0.489). Compare the two current rates before you move money.
• Treasury money market funds. California exempts a fund’s exempt-interest dividends only if the fund has at least 50% of its assets in tax-exempt U.S. obligations and/or California and California municipal obligations (FTB Schedule CA instructions). Treasury-only funds often meet this test, while government funds that hold mostly repurchase agreements may not; the fund’s annual tax statement shows the exempt percentage.
• Municipal bonds. Muni interest is generally free of federal tax (IRC 103). California taxes interest from other states’ bonds, so a California resident gets the full benefit only from California issuers. Munis carry price and credit risk, so they fit money you will not need next month.

Washington families get less from the state exemption today, because there is no state tax on interest to avoid in 2026. The federal rate is the same for both states.

The decision: how much cash, and where it sits

Most of the tax drag on cash comes from holding more than the family needs. A few questions settle it:

1. What is the real emergency number? For two W-2 earners at large tech or biotech employers, six months of fixed costs is a common target. Cash above that is usually waiting for a decision, not protecting you.
2. What is it for, and when? A down payment in 8 months or a tax bill in April can sit in T-bills or a Treasury money market fund. Money with no date usually belongs in the long-term plan.
3. Is your RSU tax already covered? Many employers withhold a flat 22% federal on RSU income (the flat rate is optional, but 37% is mandatory on supplemental wages above $1 million in a year), which is often short of a 37% bracket (IRS Publication 15). Some families hold a large HYSA balance as an informal tax reserve. That is reasonable, but it should be sized to the actual shortfall.
4. Is it insured? FDIC coverage is $250,000 per depositor, per insured bank, per ownership category. Joint accounts are a separate category, insured up to $250,000 for each co-owner’s share (FDIC). Balances above those limits may call for a second bank or Treasuries.

Savings in your children’s names

Interest in a custodial (UTMA) savings account is the child’s income, and the kiddie tax sets how it is taxed. For 2026, the first $1,350 of a child’s unearned income is tax-free, the next $1,350 is taxed at the child’s rate, and anything over $2,700 is taxed at the parents’ rate (Rev. Proc. 2025-32; Form 8615 instructions). A $50,000 UTMA savings balance at 4% earns $2,000, which stays under the $2,700 line. Remember that UTMA money becomes the child’s at 18 to 21 in California (up to 25 through a will or trust) and at 21 for most Washington gifts (the transferor can extend it to 25 when first naming the custodian). See our guide to UTMA withdrawal tax rules before funding one.

What to write down for your kids

Your children will see that you keep cash in the bank. They will not see why that amount, why that account, or why you moved it to Treasuries the year rates changed. A one-page note in your FamilyKnowledge® Library that covers your cash target, where it sits and the after-tax math takes ten minutes and outlasts any conversation. As Kevin Luu puts it: “Your kids don’t need to inherit your portfolio. They need to inherit your decision-making process.”

Common questions

Do I pay tax on HYSA interest if I don’t withdraw it?

Yes. Interest is taxable in the year it is credited to your account and available to you, even if you never move it out. That is why a HYSA can create a tax bill in a year you did not touch the money. Your 1099-INT shows the amount credited during the calendar year, and that is what goes on your 2026 return.

Is HYSA interest subject to the 3.8% NIIT?

Yes. Interest is net investment income. For married couples filing jointly, the 3.8% tax applies to the smaller of your net investment income or the amount your modified AGI exceeds $250,000. At household incomes of $600,000 and up, the full interest amount is almost always subject to it, which is why the federal rate on interest can reach 40.8%.

Can I avoid tax on HYSA interest?

Not on a regular HYSA held in a taxable account. You can lower the rate by holding cash in Treasuries (no state tax), a qualifying Treasury money market fund, or in-state municipal bonds, and by keeping less idle cash overall. Tax-advantaged accounts like a 401(k) or HSA shelter interest, but those are for long-term money, not an emergency fund.

Next step

Pull last year’s 1099-INT forms, add them up, and multiply by your combined marginal rate from the tables above. If the number surprises you, compare your cash balance to a six-month target and look at the Treasury alternative. For help sizing cash against RSU tax and your broader plan, our tax management and investment and risk management services cover it, and our guide on reducing modified adjusted gross income explains the deductions that can move your bracket.

This is general education, and the right move depends on your family’s full financial picture.

Written by

Kevin Luu

Co-Founder and Chief Learning Officer, Bright Advisers

Kevin has advised high-income W-2 tech and biotech families since 2015, and leads the education-first Age Five Family Office from Brea, California.

Connect on LinkedIn →  · About Kevin