What Is an 83(b) Election? The 30-Day Tax Form Founders Can’t Afford to Miss

Most tax deadlines give you some room. You can file an extension, pay a penalty, or fix a mistake with an amended return. The 83(b) election doesn’t work that way. You get 30 days, and if you miss them, there’s generally no going back.

I first heard about this form from a founder who described it as “the one piece of paper I’d tell every cofounder to file before they do anything else.” At the time, that sounded dramatic. After reading how the tax math plays out when someone skips it, I understood why. If you’re getting startup stock that vests over time, this is one of the few forms where a missed deadline can turn into a very large tax bill years later.

I’m not a tax advisor or an attorney, and this isn’t tax advice. Everyone’s situation is different, so talk to a qualified tax professional before deciding whether to file an 83(b) election.

The Problem the 83(b) Election Solves

To understand the election, you have to start with how vesting works. Founders and early employees often receive stock that’s subject to a vesting schedule. The shares are issued up front, but the company can take back the unvested portion if the person leaves early. A common setup is four years of vesting with a one-year cliff.

The tax code treats stock like that as property subject to a “substantial risk of forfeiture.” Under the default rule in Section 83 of the Internal Revenue Code, you don’t owe tax when you first receive it. Instead, each time a batch of shares vests, the value of those shares on that date counts as ordinary income, minus whatever you paid for them.

That sounds generous until the company starts growing. If your shares were worth a fraction of a penny when you got them but have become valuable by the time they vest, you owe ordinary income tax on the higher value, year after year, even though you haven’t sold anything and may not have any cash from the stock.

What the 83(b) Election Does

Filing an 83(b) election tells the IRS you want to be taxed on the stock right away, when you receive it, instead of as it vests. You pay tax now on the difference between the shares’ fair market value and what you paid for them. After that, the vesting itself doesn’t trigger any more tax. You won’t owe anything again until you sell, and at that point any growth is generally treated as a capital gain.

For a lot of founders, the upfront tax is zero or close to it. If you receive shares at the very beginning of a company’s life and pay their full fair market value, even if that’s only a few hundred dollars, there’s no gap between value and price, so there’s no income to report. You’ve essentially locked in a tax bill of nothing in exchange for giving up the default treatment.

Filing also starts the clock on your capital gains holding period from the date you receive the shares. That matters for long-term capital gains rates, and it can also matter for certain tax benefits available to startup stock, which are worth asking your tax advisor about.

An Example

Say you and a cofounder form a company, and you each get 4 million shares that vest over four years. The shares are worth $0.0001 each when they’re issued, so you pay $400 for yours, which is their full value.

If you file an 83(b) election, you report $0 of income, because you paid exactly what the shares were worth. From then on, vesting doesn’t create any tax.

Now imagine you don’t file. The company raises money on SAFEs, and later a priced round, and the value of the common stock climbs to $1 a share. Every year, another million of your shares vests. Each of those vesting dates could create around $1 million of ordinary income on paper, taxed at your regular income tax rate, and you’d owe that tax even though the stock is illiquid and you can’t sell it to cover the bill. That’s the scenario the election is designed to prevent.

The 30-Day Deadline

The election has to be made within 30 days of the date you receive the stock. Weekends and holidays count. There’s generally no extension, and the IRS doesn’t accept late elections except in very unusual circumstances. Once made, the election is also very hard to undo.

If you’re an employee exercising stock options early, before they vest, the same idea applies, and the 30 days usually run from the exercise date. If you’re not sure what date your clock started, ask the company or your lawyer immediately rather than guessing.

How to File

For years, filing meant mailing a signed letter to the IRS by certified mail and keeping the receipt forever. The process has gotten easier. In late 2024, the IRS released Form 15620 as a standard form for the election, and in 2025 it started allowing that form to be filed online. The law firm Goodwin has a helpful summary of how online filing works, and the form itself is available through the IRS mobile-friendly forms portal, which requires signing in with an ID.me account.

You can still file by mail if you’d rather, but use only one method so the IRS doesn’t receive two elections for the same stock. Either way, you also need to give a copy to the company that issued the shares, and keep a copy with your own records. Save the IRS confirmation if you file online. Years from now, during a financing round or an acquisition, someone may ask you to prove you filed, and having that confirmation handy saves a lot of stress.

The Risks

The 83(b) election isn’t free of downside, and I think it’s worth being honest about that.

If your stock is already worth a meaningful amount when you receive it, and you pay less than that value, filing means paying tax immediately on the difference. If you later leave before your shares vest and the company takes the unvested shares back, you generally can’t get that tax back. The same is true if the company fails and the stock ends up worthless. You’d have paid tax on value that never materialized.

That’s why the election is such a clear call when shares are worth almost nothing at the start, and a harder judgment call when they already carry real value. Timing matters a lot here.

When It Doesn’t Apply

The election is for property you actually receive that’s subject to vesting, like restricted stock or early-exercised options. It generally doesn’t apply to restricted stock units, since those aren’t shares until they settle, and it doesn’t apply to ordinary stock options you haven’t exercised. It also isn’t needed if your shares are fully vested when you get them, because there’s no future vesting to be taxed on.

Why Investors Care

This isn’t just a personal tax issue. When a startup raises a priced round or gets acquired, the buyer’s lawyers usually check whether the founders filed their 83(b) elections. A missing election can create tax problems for the founder and withholding and reporting headaches for the company, and it’s one of those details that tends to surface at the worst possible moment. Much like making sure early contractors signed over the rights to their work, getting 83(b) elections filed on time is basic housekeeping that saves a lot of trouble later.

Final Thoughts

An 83(b) election lets you pay tax on vesting stock when you receive it instead of as it vests. For founders who get shares at a very low value, it often means paying little or nothing in tax up front and avoiding large tax bills later, with future growth taxed as capital gains when you sell. The tradeoff is that you’re betting on the stock, and if you forfeit the shares or the company fails, the tax you paid doesn’t come back.

Whatever you decide, decide quickly. The 30 days start when you receive the stock, not when you get around to thinking about it. If you’ve just been issued shares that vest, put a reminder on your calendar today and get a tax professional on the phone this week.