RSUs, ISOs, and ESPP: How Bay Area Tech Workers Get Their Stock Compensation Taxes Wrong (and What It Costs Them)

You cleared $280,000 last year between salary and stock vesting. You filed your return yourself or used a general CPA, and you thought you were done. Then you got a notice from the IRS. Or you realized in April that you owe $15,000 more than expected. Or you exercised ISOs and had no idea that AMT was about to take a bite out of money you haven’t even received yet. Tax Crunch works with tech workers across the Peninsula and San Francisco Bay Area whose stock compensation creates tax situations that standard tax software and generalist CPAs routinely get wrong. The mistakes aren’t small, and they’re almost always avoidable.

RSUs: The “Simple” One That Still Trips People Up

Restricted stock units are the most common form of equity compensation at Bay Area companies. The tax treatment seems straightforward: RSUs are taxed as ordinary income when they vest, and your employer reports the income on your W-2 and withholds taxes at the time of vesting.

The problem is that the default withholding rate on RSU vesting is typically 22 percent for federal taxes, regardless of your actual marginal rate. If your combined salary and RSU income puts you in the 32 or 35 percent bracket, which it easily does for mid-level and senior engineers at companies along the Peninsula and in San Francisco, you’re being underwithheld by 10 to 13 percentage points on every vest. Multiply that gap across four quarterly vesting events and $150,000 in annual RSU income, and you’re looking at $15,000 to $20,000 in additional tax due at filing time. People who don’t anticipate this get blindsided every April.

The second RSU mistake is subtler and more expensive. When you sell RSU shares after vesting, you owe capital gains tax on any appreciation between the vesting price and the sale price. Your cost basis is the fair market value on the vesting date, and your broker reports this on Form 1099-B. But some brokers report the cost basis as zero or leave it blank, which means TurboTax or your general CPA may record the entire sale proceeds as gain rather than just the appreciation since vesting. If you vested $50,000 in shares and sold them a week later for $50,200, your actual taxable gain is $200. With an incorrect zero cost basis, the software reports $50,200 in gain, and you pay tax on income that was already taxed at vesting through your W-2. This double-reporting error happens constantly, and taxpayers who don’t catch it overpay by thousands.

ISOs: Where the Real Complexity Lives

Incentive stock options are less common than RSUs at large public companies but still widely used at startups and pre-IPO firms across the Bay Area. The tax treatment is favorable on paper: you don’t owe regular income tax when you exercise ISOs, and if you hold the shares for at least one year after exercise and two years after the grant date, the profit qualifies for long-term capital gains rates when you sell.

The catch is the Alternative Minimum Tax. When you exercise ISOs and hold the shares, the spread between the exercise price and the fair market value at exercise is an AMT adjustment. It’s not income for regular tax purposes, but it is income for AMT purposes. If you exercise a large block of ISOs in a year when the stock price is high, the AMT hit can be enormous, and it’s due on income you haven’t actually realized because you haven’t sold the shares.

This is what destroyed people during the dot-com bust. Engineers exercised ISOs when their company’s stock was at $80, owed AMT on the spread, then watched the stock fall to $5. They owed tax on phantom gains they never received. The mechanics haven’t changed. If you’re at a pre-IPO Bay Area company and you’re thinking about exercising ISOs, the AMT calculation needs to happen before you exercise, not after.

The other ISO trap is the disqualifying disposition. If you sell the shares before meeting both holding period requirements, the favorable capital gains treatment evaporates and the spread at exercise gets taxed as ordinary income. People who exercise ISOs and sell quickly to diversify or cover expenses sometimes don’t realize they’ve converted what should have been a capital gain into a much higher ordinary income tax bill.

ESPP: Small Discount, Surprising Tax Complexity

Employee Stock Purchase Plans let you buy company stock at a discount, typically 15 percent below the market price. Many tech workers treat ESPP as free money: buy at a discount, sell immediately, pocket the difference. The tax consequences of that sell-immediately strategy are manageable but often reported incorrectly.

ESPP shares have a unique cost basis calculation that depends on when you sell relative to the offering period. If you sell within the qualifying holding period (two years from the offering date and one year from the purchase date), the disposition is disqualifying, and the discount is taxed as ordinary income. If you hold long enough for a qualifying disposition, the tax treatment is more favorable but the calculation of ordinary income versus capital gain depends on the stock price at the offering date versus the purchase date versus the sale date.

Most tax software handles this poorly because the 1099-B from your broker doesn’t reflect the ESPP-specific cost basis adjustments. The reported cost basis is usually just the discounted purchase price, which understates your actual basis and overstates your gain. If you’re not manually adjusting the basis on your return using Form 8949, you’re likely overpaying.

For Bay Area workers participating in ESPP at companies like Salesforce, Google, or any of the Peninsula biotech firms, the annual amounts may seem modest per purchase period, but they add up across years of participation. Getting the basis right on every lot matters.

California Makes Everything More Expensive

Every stock compensation mistake that costs you federally costs you again at the state level. California’s top marginal rate is 13.3 percent, and there’s no preferential rate for capital gains. All capital gains in California are taxed as ordinary income. That means the federal incentive to hold ISOs for long-term capital gains treatment is partially undermined by California’s flat treatment.

California also taxes stock compensation based on where the work was performed during the vesting or service period, which creates complications for anyone who transferred to a Bay Area office from another state during a vesting schedule, or who worked remotely from California for a company headquartered elsewhere. The allocation rules are specific and frequently misapplied.

How Tax Crunch Handles Stock Compensation for Tech Workers

Joseph Chan, the CPA and attorney who runs Tax Crunch, has supervised tax filings involving stock compensation for Fortune 500 companies and their executives. That background means the firm understands the interaction between equity compensation, AMT, California source rules, and the broker reporting gaps that create errors on individual returns.

Tax Crunch reviews every RSU vesting event for correct cost basis reporting. For ISO holders, the firm models the AMT impact of proposed exercises before you commit, so you can make informed decisions about how many options to exercise and when. For ESPP participants, the basis adjustments are calculated lot by lot using the actual offering period dates, not just the numbers your broker reports.

If you’ve been filing your own return or working with a CPA who doesn’t specialize in equity compensation, it’s worth having your last two or three returns reviewed. The double-reporting errors and basis mistakes described above leave a recoverable trail. Amended returns can recapture overpayments within the IRS statute of limitations.