The 30-Day Window That Costs Startup Employees Hundreds of Thousands in Taxes

Startup employees who receive restricted stock face one of the most consequential 30-day windows in personal finance. The 83(b) election is a one-page IRS filing that allows an employee or founder who receives unvested stock or restricted equity to pay income tax on the grant’s current value rather than its future value at vesting. Most people learn about it from a colleague, lawyer, or Reddit thread after the fact. Those who miss it often regret it deeply.

A post on r/startups captured the situation plainly: a user thought their equity grant window was 90 days. It is 30. “This has haunted me for the last [year and a half],” they wrote. The comments offered no relief. There is no late filing option, no IRS exception, and no appeals process.

The Tax Trap Hidden in Your Equity Grant

• Who this affects: Startup employees and founders who receive restricted stock (actual shares subject to a vesting schedule, not RSUs)
• The core decision: File an 83(b) election within 30 days of the grant date, or pay ordinary income tax on the value of each tranche as it vests
• What is at risk: Potentially tens or hundreds of thousands of dollars in avoidable tax, plus loss of long-term capital gains treatment on future appreciation
• The deadline: Absolute and non-negotiable, set by statute

The strategic logic is straightforward: at grant, founders typically receive shares at a fraction of a penny, so the tax bill on an 83(b) election may be zero or negligible. The election locks in the tax moment at the lowest possible valuation.

How a $1 Million Grant Becomes a Six-Figure Tax Bill

Without the 83(b) election, ordinary income tax is owed on the fair market value of each tranche as it vests. That sounds abstract until you run the numbers on a real startup trajectory.

If the company grows from a $1 million valuation at grant to a $100 million valuation by the time of vesting, an employee who received 100,000 shares will owe ordinary income tax on each vested tranche at the $100 million valuation, potentially hundreds of thousands of dollars in tax on illiquid shares they cannot yet sell. The cruelty is the word “illiquid.” The shares have not been sold. There is no cash in hand. But the IRS bill arrives anyway.

The top ordinary income tax rate for 2026 is 37%. Long-term capital gains rates top out at 20% for high earners. The gap between those rates and ordinary income rates, applied to several hundred thousand dollars of vested stock value, is the difference between a manageable tax event and a financial emergency. Filing the 83(b) election converts future appreciation from ordinary income into long-term capital gains, provided the shares are held for more than one year after the grant date.

The election also starts the holding period clock immediately. Without it, the clock resets at each vesting event, meaning shares that vest four years into a job may not qualify for long-term treatment until a year after that vesting date.

Restricted Stock, RSUs, and the Tax Outcomes That Separate Them

File the 83(b) election within 30 days

This is the right move for most restricted stock recipients at early-stage startups. The tax owed at grant is typically negligible because the shares are worth very little. All future appreciation is taxed at long-term capital gains rates rather than ordinary income rates, and the holding period starts immediately. The only real risk is company failure, in which case the small tax paid at grant is a sunk cost. For a company with genuine growth potential, that is an acceptable tradeoff.

Skip the election and pay tax at vesting

This path makes sense only if the company is unlikely to appreciate significantly between grant and vesting. For most startup employees, that assumption defeats the purpose of taking equity compensation. Skipping the election is rarely a deliberate strategic choice. It is usually the result of not knowing the election existed.

The RSU situation

RSUs cannot benefit from 83(b) elections. The election is only available for restricted stock, which means actual shares subject to vesting. RSUs are promises to deliver shares, not actual shares, so the income recognition rules are different and the 83(b) election does not apply. Employees who receive RSUs instead of restricted stock face a different tax structure entirely, and the 30-day window is irrelevant to them. Knowing which type of equity you hold is the first question to answer.

Filing the 83(b): The 30-Day Clock and What the IRS Requires

The 30-day window is absolute. The IRS provides no exceptions for late 83(b) elections. An employee who receives restricted stock on January 1 must file by January 31. Filing on February 1 means the election is permanently forfeited.

The IRS accepts electronic filings through Form 15620 via its online portal. The 30-day deadline and the obligation to provide a copy to the employer remain unchanged under the new electronic system. If filing electronically, save the IRS confirmation page. A copy must also be provided to the employer and attached to the employee’s tax return for the year of the grant.

For those who prefer paper, the old approach still works. The 83(b) election must be mailed to the IRS service center where the employee files their tax return. Because the IRS does not acknowledge receipt, certified mail with return receipt is essential. This creates a timestamped record that the filing was sent within the window.

Why Most People Miss the Window and How to Make Sure You Don’t

The most expensive error is simply not knowing the clock is running. Many startups do not proactively tell new employees about the 83(b) election. The equity grant paperwork arrives, gets skimmed, and 31 days later the window is gone. The employee finds out about the election months later when talking to a tax preparer or reading a forum post.

The day restricted stock is granted, set a calendar reminder for day 25 of the 30-day window. Use that buffer to gather the grant documents, complete Form 15620 online or prepare the paper version, and confirm the filing with your employer. The election itself takes less than an hour to complete. The tax savings it protects can be life-changing.