Tax-Free Investments and 529 Plan Alternatives for High-Income Families

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

For a California or Washington family earning $750,000 or more, the tax-free investments that actually work are a 529 plan, a backdoor Roth IRA, a mega backdoor Roth inside a 401(k), a health savings account (tax-free federally only, if you live in California), and municipal bonds held in a taxable account. If you are looking for 529 plan alternatives, the realistic ones at this income are the two Roth routes and a tax-efficient taxable account. A Coverdell ESA and the education exclusion for savings bonds are usually closed to you by income limits.

Most “best tax-free investments” lists are written for households far below this income. They recommend accounts you cannot contribute to and skip the ones that matter most for a physician, biotech or tech family with two young children. This guide sorts the list by what is open to you, shows how each one is taxed in California versus Washington, and works through one family’s numbers for 2026.

Which tax-free accounts are open to a $1 million household

Income limits decide most of this. Here is how the usual list looks once you apply them for 2026, married filing jointly.

So the working list is five items, not ten. The order you fund them in matters more than finding a sixth.

Roth accounts: the most flexible 529 alternative

A Roth IRA or Roth 401(k) balance grows tax-free and comes out tax-free in retirement. At this income your Roth IRA money arrives by conversion rather than direct contribution. IRS ordering rules treat regular contributions as coming out first, then conversions, then earnings. The part of a conversion you were not taxed on (in a clean backdoor Roth, nearly all of it) can generally be withdrawn without tax or the 10% additional tax; any part that was taxable at conversion faces the 10% tax if withdrawn within five years and before age 59½ (IRS Pub 590-B). Earnings come out last. That is why families use Roth money as a backstop for college if the 529 falls short. That flexibility is what makes it the most common 529 alternative for high earners.

The backdoor Roth IRA

Each spouse contributes $7,500 for 2026 to a traditional IRA with no deduction, then converts it to a Roth IRA. The trap is the pro-rata rule. If the spouse converting holds pre-tax money in any traditional, SEP or SIMPLE IRA on December 31 of the conversion year, part of that spouse’s conversion becomes taxable. The rule applies to each spouse separately, so one spouse’s old IRA does not affect the other’s conversion. Form 8606, filed for each spouse, tracks this (IRS Pub 590-A). Rolling old pre-tax IRA money into a current 401(k), if the plan accepts it, usually clears the way.

The mega backdoor Roth

This is the larger lever. For 2026 the total that can go into your 401(k) from all sources is $72,000, excluding catch-ups. Subtract your $24,500 pre-tax or Roth deferral and your employer’s contributions, and what is left can go in as after-tax money, then be converted to Roth. Many large employers in biotech and tech offer it. Many hospital and university plans do not. Check your summary plan description for both “after-tax contributions” and “in-plan Roth conversion” or “in-service withdrawals”.

529 plans: tax-free for college, less so for K-12 in California

Federally, 529 earnings are tax-free when spent on qualified education, and there is no income limit to contribute. There is also no federal annual contribution limit (each state’s plan caps the total balance per beneficiary). What people call a limit is the gift tax annual exclusion: $19,000 per donor per child for 2026, so two parents, each giving $19,000 from their own or community funds, can put in $38,000 per child without filing a gift tax return. A five-year election lets each parent front-load up to $95,000 per child, or $190,000 as a couple, reported on Form 709 (Form 709 instructions).

California residents need to know three things:

• No state deduction. California gives no deduction for 529 contributions for 2026. Growth is still free of California tax when used for college.
• K-12 tuition is not qualified in California. Federal law now treats more elementary and secondary school costs as qualified 529 expenses, but California does not conform. The earnings portion of a K-12 withdrawal is taxable in California and subject to an additional 2.5% state tax (FTB Form 3805P instructions).
• The 529-to-Roth rollover is federal only. Federal law allows a limited direct rollover from a 529 open more than 15 years to the beneficiary’s Roth IRA, using only contributions (and their earnings) made more than 5 years earlier and staying within the annual Roth limit (IRS Pub 970). California taxes the rolled-over earnings and adds the 2.5% tax (same FTB source).

Washington has no state income tax for 2026, so federal 529 rules are the whole story there for now. Washington has enacted a 9.9% income tax on AGI over $1,000,000 starting in 2028, and the state has not yet published how it will treat 529 withdrawals (WA DOR).

HSAs: a strong federal account that California taxes

With an HSA-eligible high-deductible plan, a family can contribute $8,750 for 2026 (IRS Rev. Proc. 2025-19). Federally, contributions are deductible, growth is untaxed, and withdrawals for medical costs are tax-free. Families who pay current medical bills from cash and let the HSA stay invested treat it as a long-term account.

California does not recognize HSAs. Contributions made through payroll are added back to California wages, contributions you make directly get no California deduction, and interest, dividends and gains inside the account are taxable in California each year (FTB Schedule CA instructions). The federal benefit still makes it worth funding for most California families on a qualifying plan, but a California HSA is not a tax-free investment at the state level. Keep low-turnover funds in it to limit the yearly state tax. Washington residents get the full federal benefit with no state tax for 2026.

Municipal bonds: where you live changes the answer

Interest on most state and local government bonds is exempt from federal income tax, and it is not part of the 3.8% Net Investment Income Tax. California exempts interest on California bonds but taxes interest on bonds from other states (FTB Publication 1001). So a California family usually compares California munis against taxable bonds. A Washington family compares national munis, since there is no state income tax to avoid in 2026.

Illustration with hypothetical yields (not a forecast):

• California family in the 37% federal bracket and the 11.3% California bracket. Combined rate on taxable bond interest: 37% + 3.8% + 11.3% = 52.1%. A California muni yielding 3.0% is worth about the same as a taxable bond yielding 6.3% (3.0% divided by 0.479).
• Washington family in the 37% federal bracket. Combined rate: 37% + 3.8% = 40.8%. A national muni yielding 3.2% matches a taxable bond yielding about 5.4% (3.2% divided by 0.592).

At these brackets, munis usually win for the bond portion of a taxable account. They make little sense inside a Roth or 401(k), where interest is already sheltered.

Worked example: a $1.1 million California household in 2026

Assumptions (illustrative): Priya works at a South San Francisco biotech company and earns $520,000 in salary, bonus and RSUs. Mark is a hospital physician earning $580,000. Their children are 4 and 7. Both have 401(k) or 403(b) plans. Priya’s plan allows after-tax contributions with in-plan Roth conversion, and her employer contributes $12,000. Mark’s plan does not allow after-tax contributions. They are on a family HSA-eligible plan. After pre-tax deferrals their federal taxable income stays above $768,700, so their federal bracket for 2026 is 37%.

That is $50,500 a year of new Roth money and up to $76,000 of 529 funding without touching their lifetime gift exemption. The two 401(k)/403(b) deferrals of $24,500 each are tax-deferred rather than tax-free, and sit alongside this.

The decision Priya and Mark actually face is the split between 529 and Roth. If they fund the 529s heavily and a child gets a scholarship or skips a four-year degree, the leftover money is less flexible than Roth dollars, and California taxes the 529-to-Roth rollover. If they lean on Roth and taxable accounts instead, they give up tax-free growth on the education money but keep control. Many families at this income fund 529s to a target (for example, four years of in-state public college in today’s dollars per child) and put the rest into Roth and taxable accounts.

What to skip, or keep separate

• Coverdell ESAs and education savings bonds. Income limits usually rule them out at this income.
• Permanent life insurance sold as a tax-free investment. Treat it as an insurance and estate question first, reviewed on its own costs, not as a substitute for the accounts above.
• A UTMA as the main college account. A UTMA gives the child legal control at 18 in California by default (up to 21 for a lifetime gift, or 25 for a will or trust transfer, only if written into the transfer) and at 21 for a gift in Washington (RCW 11.114.200), and its income falls under the kiddie tax: for 2026, unearned income over $2,700 is taxed at the parents’ rate. See our UTMA withdrawal tax rules.

Common mistakes we see at this income

• Doing a backdoor Roth while holding an old rollover IRA, which can make much of the conversion taxable.
• Assuming an HSA is tax-free in California.
• Using a California 529 for private K-12 tuition without planning for the state tax on the earnings.
• Holding California munis inside a 401(k) or Roth, where the tax exemption is wasted.
• Never checking whether the 401(k) allows after-tax contributions, which can leave $30,000 or more of Roth room unused each year.

What to write down for your children

The accounts are the easy part. The harder part is that a child who inherits a Roth IRA or a 529 at 22 inherits the balance without the reasoning. Write one page per account: why you opened it, what it is for, what you decided when a choice came up (for example, why you stopped funding the 529 at a target), and what you would want done with any leftover money. As Kevin Luu puts it: “Your kids don’t need to inherit your portfolio. They need to inherit your decision-making process.” That page belongs in your FamilyKnowledge® Library, and our Age Five Wealth Education work starts from it.

Frequently asked questions

What is the best 529 alternative for high-income parents?

For most families earning over $750,000, the best alternative is Roth money: the backdoor Roth IRA and, if the plan allows it, the mega backdoor Roth. Untaxed conversion amounts can generally be withdrawn without tax, earnings stay sheltered, and anything not used for school stays invested for retirement. A taxable brokerage account with low-turnover index funds is the next option, with no restrictions on use.

Are municipal bonds tax-free in California?

Interest on California state and local bonds is generally free of both federal and California income tax. Interest on bonds from other states is exempt federally but taxable in California, including when it passes through most mutual funds. That is why California families often use California-only muni funds, while Washington families, with no state income tax for 2026, can use national funds.

Is a 529 still worth it in California with no state deduction?

Often yes. Growth is free of federal tax and California tax when used for college, and at a combined top rate above 50% on ordinary income, sheltering decades of growth can matter more than a deduction would. The case is weaker if you mainly plan to use it for K-12 tuition, since California taxes those earnings.

Next step

Pull your 401(k) summary plan description and check for after-tax contributions and in-plan Roth conversions. That one answer usually decides how much of the list above you can use. For help sequencing these accounts with your equity compensation and taxes, see our tax management and retirement and employee benefits services, or read how taxable brokerage accounts are taxed. You can also start with a Tax & Wealth Assessment.

This is general education, and the right move depends on the family’s full 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