If you hold Anthropic RSUs or stock options, the IPO can create a large taxable event in a single day, and standard payroll withholding usually will not cover the full bill. Anthropic made its S-1 public on October 26, 2026, and press reports point to pricing in mid-November. For employees across San Francisco, the Peninsula, the South Bay and the East Bay, the next 60 days are the window to plan.
Key takeaways
The Bay Area tax and wealth management teams at SD Mayer help tech employees handle each of these steps.
The tax result depends on what you hold. Most current employees hold RSUs; earlier employees may also hold stock options.
|
Equity type |
When it's taxed |
How it's taxed |
What to watch |
|---|---|---|---|
|
RSUs (time-vested, IPO-triggered) |
At settlement, when the IPO registration becomes effective |
Ordinary wage income on the full share value; federal, California, Social Security/Medicare and CA SDI apply |
One-day income spike; under-withholding; later gain or loss is capital |
|
Incentive stock options (ISOs) |
Not at exercise for regular tax; at sale |
Spread at exercise is an AMT preference item; qualifying sale (2 yrs from grant, 1 yr from exercise) gets long-term capital gain |
AMT bill without cash; disqualifying sales during the lockup convert gain to ordinary income |
|
Non-qualified stock options (NSOs) |
At exercise |
Spread (market value minus strike) is ordinary wage income |
Exercising before vs. after the IPO price is set changes the bill |
|
Shares already owned (early exercise, prior tender, ESPP) |
At sale |
Capital gain; long-term if held over one year |
Holding-period dates, cost basis records |
Per the S-1, RSUs whose service-based vesting is already met will be net settled at effectiveness: the company withholds shares to cover estimated taxes and delivers the rest. You owe tax on the gross value, not the net shares you receive.
The S-1 also describes a new Class E common stock for employees. It carries limited voting rights and no economic rights, so it is not expected to create taxable income on its own; confirm with your advisor once final documents are issued.
A note on QSBS: the Section 1202 exclusion depends on the company's gross assets when shares were issued, and California does not conform to it. Most Anthropic employee shares are unlikely to qualify, but early holders should have their issuance dates reviewed.
Bay Area employees face some of the highest combined tax rates in the country on IPO equity income. Here is how the layers stack for 2026.
|
Tax layer |
2026 rate on equity wage income |
Notes |
|---|---|---|
|
Federal income tax |
Up to 37% |
Top bracket for high earners |
|
Medicare + Additional Medicare |
1.45% + 0.9% |
Additional 0.9% applies above $200,000 of wages (single) |
|
California income tax |
Up to 13.3% |
Includes the 1% Mental Health Services Tax on income above $1 million |
|
California SDI |
1.3% |
No wage cap since 2024 |
|
City income tax (SF, San Jose, Oakland) |
None |
San Francisco's payroll and gross receipts taxes fall on employers, not employees |
On top of these, later gains on shares you sell are subject to capital gains tax and the 3.8% Net Investment Income Tax. California taxes capital gains as ordinary income, up to 13.3%.
Payroll withholds federal tax on equity income at a flat 22% up to $1 million and 37% above that, plus California's 10.23% supplemental rate. Your actual marginal rate can be above 50%.
Illustration (hypothetical): an employee already in the top bracket has $2 million of RSUs settle at IPO. Withholding for income taxes is roughly $795,000 ($590,000 federal + $204,600 California). The actual income tax on that $2 million at 37% + 13.3% is roughly $1,006,000. The shortfall is about $211,000, due by April 15, 2027, plus potential underpayment penalties. Actual results depend on your full tax picture.
California taxes equity compensation based on where you worked between grant and vesting. If you earned RSUs while working in the Bay Area and then move to Nevada, Texas or Washington, California can still tax the California-sourced portion. Residency changes need careful documentation.
Employees are typically barred from selling for up to 180 days after the IPO, though the S-1 permits share sales to cover tax withholding. After the lockup, insider trading windows and blackout periods still limit when you can sell. A 10b5-1 trading plan can automate sales on a set schedule. Meanwhile, the tax is owed at today's value even if the stock falls before you can sell.
SD Mayer is a Bay Area CPA firm headquartered in San Francisco, with offices in San Mateo, Menlo Park and San Leandro. Our tax professionals work with tech employees on equity compensation every filing season. For Anthropic employees, we typically:
We ask clients to share documents only through our secure portal (which we can provide you), never by plain email.
The biggest financial risk after an IPO is usually concentration: most of your net worth tied to one stock you cannot sell for months. SD Mayer's wealth management team works alongside our tax team so investment decisions and tax consequences are planned together.
Set aside the tax money first. Before any spending or investing, we help you reserve cash for the April 2027 balance due and estimated payments.
Build a diversification plan. We set target sale schedules after the lockup, using 10b5-1 plans where appropriate, so selling follows a plan rather than headlines. We also evaluate exchange funds and other strategies that reduce single-stock risk while deferring gains.
Invest with taxes in mind. We place assets in the right account types, use tax-loss harvesting, and consider California municipal bonds for income that is exempt from both federal and California tax.
Make charitable giving count. The S-1 describes a company program that matches employee equity pledges to charity. Giving appreciated shares to a donor-advised fund or charitable remainder trust can avoid capital gains and create a deduction. Starting in 2026, itemizers must exceed a 0.5%-of-AGI floor, and top-bracket donors' deductions are capped at a 35% benefit, so timing gifts matters.
Plan the big goals. We map out a Bay Area home purchase, education funding, early retirement or a sabbatical against realistic after-tax numbers.
Protect what you've built. We coordinate with estate attorneys on wills, revocable trusts and lifetime gifting, and review insurance and asset protection.
Family office services for significant IPO wealthFor early employees and leaders whose equity becomes eight- or nine-figure wealth, a family office approach brings tax, investments, bookkeeping and estate planning under one coordinated team. SD Mayer's family office services can include:
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RSUs that have met their time-based vesting settle when the IPO registration becomes effective. The full market value of the shares is taxed as ordinary wage income in 2026, subject to federal, California, Medicare and California SDI taxes.
Often not. Federal supplemental withholding is 22% up to $1 million and 37% above, and California withholds 10.23%. High earners in the Bay Area can face combined marginal rates above 50%, leaving a balance due.
The balance is due by April 15, 2027. To avoid penalties, many employees need to make estimated payments by January 15, 2027. California filers with AGI of $1 million or more must pay 90% of their 2026 tax on time.
Not on equity you earned while working in California. California taxes RSU and option income based on the share of the vesting period you worked in the state, even after you become a nonresident.
It depends on your AMT exposure, cash available and how long you plan to hold. A tax projection that models several exercise amounts is the best way to decide.
Generally not. Employees are typically subject to a lockup of up to 180 days, except for shares withheld to cover taxes. Company trading windows also apply after the lockup ends.
IPO decisions mix tax and investment questions. Working with a firm whose CPAs and wealth advisors coordinate helps ensure sale timing, charitable gifts and diversification are planned with the tax impact in view.
The decisions with the most impact, such as option exercises, estimated payments and charitable gifts, need to happen before December 31, 2026. Schedule a confidential consultation with SD Mayer's tax and wealth management team at our San Francisco, San Mateo, Menlo Park or San Leandro office. Schedule a free consultation today.
This article is for general information only and is not tax, legal or investment advice. Figures reflect 2026 rules and press reports as of October 26, 2026; IPO terms, pricing and lockup details may change. Consult a qualified CPA, attorney or financial advisor about your situation.