The $100K ISO limit

The $100K ISO limit

Author: The Carta Team
Read time:  1 minute
Published date:  8 July 2022
Updated date:  12 April 2024
The ISO $100K limit prevents employees from treating more than $100,000 worth of exercisable options as incentive stock options in a single year. Learn more.

What is the $100K ISO limit?

The $100K ISO limit (also known as the $100K rule) prevents employees from treating more than $100,000 worth of exercisable options as incentive stock options (ISO) in a single year. 

The first $100,000 of stock options that become exercisable for an employee in a year can be issued as ISOs, and any additional stock options will be taxed as non-qualified stock options (NSO). ISOs are not taxed when exercised, so the $100K ISO limit aims to prevent abuse of this tax benefit. 

To comply with the $100K rule, your company may divide option grants that exceed the $100,000 threshold into ISO and NSO portions. This division is commonly called an ISO/NSO split. 

100k limit download illustration

Download the $100K limit guide

Why the $100K rule matters

The $100K rule could affect the amount of taxes that you will need to pay when exercising your stock options, because ISOs and NSOs are taxed differently. NSOs are usually taxed both when employees exercise (i.e. purchase) shares and when they sell them, whereas ISOs are only taxed when employees sell them.

When you exercise (i.e. purchase) NSOs, you will owe tax on the “bargain element,” or the difference between the fair market value (FMV) of your shares at exercise and the exercise price. The bargain element is taxed as compensation at your ordinary income tax rate. While you pay taxes as an employee when exercising your NSOs, your company can take a tax deduction.

In contrast, ISOs are not taxed upon exercise, and exercising does not give your company a tax deduction.

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The Carta Team
While we believe in assigning ownership at Carta, this blog post belongs to all of us.
DISCLOSURE: This post contains general information only and eShares, Inc. dba Carta, Inc. (“Carta”) is not, by means of this publication, rendering accounting, business, financial, investment, legal, tax, or other professional advice or services.  This post is not a substitute for such professional advice or services nor should it be used as a basis for any decision or action that may affect your business or interests. Before making any decision or taking any action that may affect your business or interests, you should consult a qualified professional advisor.  This post is not intended as a recommendation, offer or solicitation for the purchase or sale of any security. Carta does not assume any liability for reliance on the information provided herein.