By Kevin Luu, Co-Founder and Chief Learning Officer. Reviewed on 2026-09-30.
A financial windfall is a large, one-time sum of money that arrives outside your normal pay: an IPO or tender offer that turns RSUs into cash, a retention bonus, an inheritance, or a large gift from parents. What makes it a windfall is not the size but the timing. It lands in a single tax year, often with too little tax withheld, and the decisions you make in the first few months usually matter more than the investments you pick later.
For a two-income family in California or Washington already earning $750,000 or more, the common windfalls are equity liquidity and inheritances. This article explains how each type is taxed for 2026, works through a $2 million RSU example in both states, and lists the decisions that come first.
The four windfalls high-income W-2 families actually see
| Windfall | How it is taxed (federal, 2026) | The trap |
|---|---|---|
| RSUs delivered at an IPO, or after a lockup, or in a large vest | Ordinary wages at delivery, at your marginal rate (37% above $768,700 of taxable income for a married couple filing jointly) | Withholding is usually lower than the tax owed |
| Cash sign-on or retention bonus | Ordinary wages, withheld as supplemental wages | Same withholding gap, and it often lands in a year with a big vest |
| Inheritance of stock, a house or cash | Generally not income to you when received; basis is generally fair market value on the date of death | Inherited traditional IRAs and 401(k)s follow separate withdrawal rules and are taxed as ordinary income when withdrawn |
| Large gift from parents | Not income to you; the giver files Form 709 for gifts above $19,000 per recipient | Gifts of appreciated stock generally carry the giver’s basis, not a fresh one |
Sources: supplemental wage rules in IRS Publication 15 (2026); brackets and the $19,000 annual exclusion in Rev. Proc. 2025-32; gifts and inheritances generally not included in income in IRS Publication 525; inherited property basis on the IRS gifts and inheritances FAQ; basis of gifted property in IRS Publication 551.
Why the withholding on an RSU windfall falls short
RSUs are taxed as wages when shares are delivered. Your employer withholds on them as supplemental wages. For 2026, federal withholding is an optional flat 22% on supplemental wages up to $1,000,000 in the calendar year, and a mandatory 37% on the part above $1,000,000 (Pub 15). A family already in the 37% bracket owes 37% on every dollar of that income, so the first $1,000,000 is under-withheld by 15 points.
Note that an 83(b) election does not apply to RSUs. It is for restricted stock and early-exercised options. RSUs are not property for tax purposes until the shares are delivered (Treas. Reg. 1.83-3(e)).
Worked example: $2 million of RSUs at an IPO, California versus Washington
Assumptions: a married couple filing jointly with two children, ages 4 and 8. Combined salaries of $850,000. One spouse’s employer goes public and $2,000,000 of RSUs are delivered in 2026. Both spouses are already over the Social Security wage base ($184,500 for 2026) from salary, so no extra Social Security tax applies. No other supplemental wages this year. Figures are rounded estimates for illustration, not a tax return.
| Tax on the $2,000,000 RSU income | California family | Washington family |
|---|---|---|
| Federal income tax at 37% | $740,000 | $740,000 |
| Medicare 1.45% plus 0.9% Additional Medicare Tax | $47,000 | $47,000 |
| State income tax | about $257,000 (2025 CA schedule, incl. 1% over $1M) | $0 (no wage income tax in 2026) |
| CA SDI at 1.3%, no wage cap | $26,000 | n/a |
| WA Cares at 0.58%, no wage cap (unless exempt) | n/a | $11,600 |
| Total tax on the windfall | about $1,070,000 (54%) | about $799,000 (40%) |
| Federal income tax withheld (22% on first $1M, 37% on the rest) | $590,000 | $590,000 |
| Federal shortfall to plan for | about $150,000 | about $150,000 |
How the California line was estimated: with about $840,000 of California taxable income before the RSUs, adding $2,000,000 moves the family through the 10.3%, 11.3% and 12.3% brackets and adds the 1% Behavioral Health Services Tax on taxable income over $1,000,000. California has not published 2026 brackets, so the 2025 schedule from the FTB is used. California also taxes capital gains as ordinary income, so later growth on the shares is taxed at the same rates (FTB).
For the Washington family, the picture changes once shares are held and sold at a gain. Washington taxes long-term capital gains at 7% above a standard deduction ($278,000 for 2025, the latest published figure) and 9.9% on taxable gains above $1,000,000 (WA DOR). Washington has also enacted a 9.9% income tax on AGI over $1,000,000 starting January 1, 2028 (WA DOR). For a family with multi-year vesting, that date belongs in the plan now.
The first 90 days: five decisions in order
- Set the tax aside first. Move the estimated shortfall, plus state tax not covered by withholding, into a separate account. Do not count it as yours.
- Fix the underpayment exposure. For 2026, if your 2025 AGI was over $150,000, you generally avoid the underpayment penalty by paying at least 110% of your 2025 tax through withholding and estimates, or 90% of your 2026 tax (Form 1040-ES (2026)). A windfall year is where this rule earns its keep.
- Decide on concentration. Selling RSU shares right after delivery creates little or no extra gain, because your basis is the value already taxed as wages. Holding is a separate bet on one company, on top of your salary and unvested grants from the same employer. See our equity compensation and investment risk pages.
- Fund the goals that have limits. Each parent can front-load up to $95,000 into a child’s 529 plan for 2026 using the five-year election (Form 709 instructions), so $190,000 per child for a couple. The election is made by filing Form 709. California gives no state deduction for 529 contributions, but growth is tax-deferred.
- Write down the reasons before you spend. A house upgrade, a sabbatical, a gift to parents: each is a fine choice when it is decided on purpose, not by default.
Inheritances: what is taxed and what is not
An inheritance of cash, stock or real estate is generally not taxable income when you receive it (IRS Pub 525), though income it later produces, such as dividends or rent, is taxable. Your basis in inherited property is generally its fair market value on the date of death, so selling soon after typically produces little gain (IRS). The exception is an inherited traditional IRA or 401(k): withdrawals are taxed as ordinary income, and at a 37% federal bracket plus California rates, the timing of those withdrawals is the real decision (IRS Pub 590-B).
A very large inheritance also changes your own estate plan. The federal exclusion is $15,000,000 per person for 2026, but Washington’s estate tax starts at a much lower level ($3,000,000 for deaths from July 1, 2026) (WA DOR). Guardianship, trusts for minor children and beneficiary designations should be reviewed after any windfall. See our estate planning page.
Common mistakes after a windfall
- Treating the gross number as the net number. In the California example, roughly half the RSU value goes to tax.
- Assuming withholding settled the bill, then finding a six-figure balance in April.
- Keeping the entire position because selling “feels like a bet against the company.”
- Buying a larger house in the same quarter, before the tax and concentration decisions are made.
- Telling the kids nothing, so the only thing they see is the new car.
What to document for your children
Children notice when money changes a household. What they rarely see is the reasoning: why you sold, what you kept, what you gave. A one-page Decision Memo written the month the money arrives, covering what you did and why, becomes something your 8-year-old can read at 16. As Kevin Luu puts it: “Your kids don’t need to inherit your portfolio. They need to inherit your decision-making process.”
That is the idea behind the FamilyKnowledge® System and our family governance work: the windfall is a one-time event, but the judgment behind it can be passed down.
Frequently asked questions
Is a windfall taxed differently from regular income?
It depends on the type. RSU income and bonuses are wages and are taxed exactly like salary, at your marginal rate, only withheld differently. Inheritances and gifts are generally not income to the person who receives them. Lottery and gambling winnings are taxable income (IRS Topic 419). The label “windfall” itself has no special tax treatment under federal law.
Should we pay off the mortgage with a windfall?
Sometimes. It trades a fixed interest rate for certainty and lower monthly costs, but it also locks cash in a house that is hard to reach in an emergency. Families with low fixed-rate mortgages often keep them and invest instead. The better order is tax set-aside first, then concentration, then the mortgage question, with the reasoning written down.
Next step
If an IPO, tender offer or inheritance is coming in the next twelve months, run the numbers before it arrives, not after. Our tax management page describes the Tax & Wealth Assessment. For how a windfall fits into longer-term planning, see the 7 stages of wealth and living off the interest of $2 million.
This is general education, and the right move depends on the family’s full picture.
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 KevinThis is part of how we approach Family Governance for high-income W-2 families at Bright Advisers.
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