If you're a founder with vesting stock, you have 30 days to make a decision that could save you tens of thousands in taxes. Don’t miss it.

Here's the problem: when a company gives you stock, the IRS taxes you on the difference between what you pay and what it's worth at the moment each chunk vests.

Not today, but in every single vesting event.

If your shares are worth $1 today and $10 when they vest two years from now, you owe ordinary income tax on $10 per share at the moment they vest. Multiply that across a four-year vesting schedule, and you're tracking down fair market value every month and writing a check to the IRS every time the company grows.

What vesting is and why your startup needs it

Vesting is a schedule that determines when you actually own your shares. You might be granted 1,000 shares on day one, but if they vest over four years, you earn them gradually over time.

The most common structure for startups is a four-year vest with a one-year cliff. Nothing vests in the first year. If a founder leaves before that anniversary, they walk away with nothing. On the one-year mark, 25% vests at once and the rest vests monthly after that.

This structure exists for a reason. Startups run on trust and long-term commitment. If a co-founder can take a significant chunk of equity and exit six months in, that's a problem for everyone still building the company. Vesting aligns incentives; it protects the team, the cap table, and the investors who will eventually review both.

Speaking of investors: VCs will require vesting schedules before they wire money. They don’t want to be left with people who don’t carry their own weight and that would complicate getting approval for important issues or hold outsized sway.

Why vesting creates a tax problem

The IRS has a specific concept called "substantial risk of forfeiture." Translation: if you might lose the shares, you don't really own them yet.

Vesting creates exactly that risk. Until shares vest, the IRS doesn't consider them yours. And until they're yours, no taxable event has occurred.

That may sound like good news, but it means your taxable events are scattered across years of vesting, when share prices may be higher or less predictable.

What the 83(b) election does

An 83(b) election tells the IRS: tax me now, on all of it, as if the vesting schedule doesn't exist.

For most early-stage founders, this is the right move. At formation, you're paying next to nothing for shares that are worth next to nothing. The delta is zero. File the 83(b), pay zero tax, and lock in your cost basis at the lowest possible point.

Everything after that gets taxed as capital gains when you eventually sell, not ordinary income as you vest.

The deadline is not flexible

You have a very inflexible 30 days from the date of grant. Not much wiggle room for exemptions or excuses for late filing.

File it where you file your 1040, send it by certified mail, keep proof, and give a copy to the company.

When it's not automatic

If there's already a gap between what you're paying and what the shares are worth, the calculus may change. You'd owe some tax today. But even then, talk with your attorney and/or CPA since you have to weigh the tax hit now against the exposure of paying ordinary income on higher values later.

But when the delta is zero? File it. No downside, significant upside.

Bottom Line:

If you're setting up a startup with vesting, and you should have vesting, get this done in the first 30 days.

It's one page, costs nothing, and skipping it is one of the most expensive mistakes a founder can make.

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