Non-Qualified Stock Options (NSOs)
A practical guide to how NSOs work, how they are taxed at exercise and sale, and what employees should weigh before acting.
NSOs are a common form of employee equity compensation. They look similar to ISOs on the surface: both give you the right to buy stock at a fixed exercise price. But the tax treatment is different.
For many employees, that tax difference is the single most important thing to understand.
How NSOs work
An NSO gives you the right to buy shares at a set strike price after vesting. If the company’s stock is worth more than the strike price, the option is “in the money.”
When you exercise, you pay the strike price and receive shares.
The main tax difference vs. ISOs
With NSOs, the spread between the fair market value and the strike price at exercise is generally treated as compensation income. In other words, exercising can create ordinary income even if you do not sell the shares right away.
After exercise, any additional appreciation or decline before sale generally affects capital gain or loss.
That makes the NSO decision tree more straightforward than the ISO tree in some ways, but not always easier.
Why employees still like NSOs
- They are widely used and flexible
- The tax rules are easier to describe than ISO rules
- They avoid the specific ISO holding-period framework
- They can still create meaningful upside if exercised thoughtfully
What to evaluate before exercising
Cash needed to exercise
You need money for the strike price.
Tax bill
Because exercise can create ordinary income, taxes may be the bigger issue than the exercise cost itself.
Liquidity
If the company is private, you may owe tax on shares you cannot easily sell.
Concentration risk
Exercising more options increases your exposure to a single company.
Common exercise approaches
Exercise and hold
You pay the strike price, recognize the compensation element, then hold the stock for future upside.
Exercise and sell
More common when liquidity is available. This can reduce cash needs and concentration.
Wait
Sometimes the best move is not to exercise yet, especially if the company is still highly uncertain or the tax cost is steep.
Common employee mistakes
Focusing only on upside
You need to model taxes, not just hypothetical future valuation.
Treating illiquid stock like public stock
A private company share may have value on paper but no ready market.
Missing deadlines after leaving
Vested NSOs can expire if not exercised within the post-termination window.
Final takeaway
NSOs are not inherently bad or good. They are a tool. The right decision depends on the spread, your cash position, the company’s prospects, and your willingness to take concentrated illiquid risk.
Related guides
Sources and further reading
- IRS Topic No. 427, Stock Options: https://www.irs.gov/taxtopics/tc427
- IRS Publication 525: https://www.irs.gov/publications/p525