Author: Maria Castillo Dominguez

Your broker sends a 1099-B when you sell ESPP shares. But the cost basis on that form is often incomplete or understated, and filing without adjusting it often means paying tax twice on the same income.

Tax season is when ESPP mistakes become expensive. The most common one is not a decision error. It is a paperwork error. Specifically, it is filing your return using the cost basis your broker reported on your 1099-B without realizing that number is often wrong.

This post explains how ESPP transactions are reported at tax time, why the 1099-B cost basis is often understated, and what you need to do to file correctly as part of your broader equity compensation financial planning.

What the 1099-B Reports

When you sell ESPP shares, your broker sends you a Form 1099-B at the end of the year. This form reports the proceeds from your sale and the cost basis your broker has on file. The IRS also receives a copy, so whatever you report on your tax return needs to reconcile with what is on the 1099-B.

For most investments, this is straightforward. You bought shares at one price, sold at another, and the gain or loss is the difference. ESPP shares are more complicated because part of your gain is treated as ordinary income and reported on your W-2. If your 1099-B does not reflect that, you may appear to owe taxes on income you have already paid tax on.

How Cost Basis Works for ESPP Shares

Your true cost basis for ESPP shares is not simply what you paid out of pocket. It is what you paid plus any amount that was already treated as ordinary income.

In a disqualifying disposition, the spread between your purchase price and the fair market value on the purchase date is added to your W-2 as ordinary income in the year you sell the shares. Your cost basis for capital gain purposes is then your original purchase price plus that spread, which equals the fair market value on the purchase date. If you sold at the fair market value, you have zero capital gain. If you sold higher, you have a capital gain on only the appreciation above the purchase date value.

If your broker only reports your actual out-of-pocket purchase price as your cost basis, your reported gain will be overstated. You will pay capital gains tax on income that is already on your W-2 as wages.

What to Look For on Your 1099-B

When your 1099-B arrives, locate the cost basis reported for your ESPP shares. Compare it to what you actually paid, the discounted purchase price, and what the stock was worth on the purchase date. If the cost basis equals only your discounted purchase price, it is understated.

The corrected cost basis should include the amount that was already taxed as ordinary income. The difference between the two, the spread, should already be on your W-2 in box 1 as wages. If you see it there, that is confirmation your employer reported it. Your job at tax time is to make sure you are not also reporting it as a capital gain.

Qualifying Dispositions and the 1099-B

Qualifying dispositions have their own reporting nuance. In a qualifying disposition, the discount portion of your gain is still taxed as ordinary income, but it shows up differently. It is reported on your W-2 in the year you sell, not the year you purchased. The amount is the lesser of: the discount at the start-of-period price, or your actual gain on the sale.

Your cost basis on the 1099-B may still show only your purchase price, which is lower than the adjusted basis. You will need to add the ordinary income component to your cost basis to avoid overstating your capital gain on Schedule D.

This is why qualifying disposition tax returns are more complicated than they first appear. The numbers come from multiple forms and need to be reconciled carefully.

Form 3922

Each year that you purchase shares through your ESPP, your employer sends you a Form 3922. This form contains the information you need to calculate your cost basis correctly: the offering period start date, the purchase date, the fair market value at both dates, your purchase price, and the number of shares purchased.

Hold onto every Form 3922 you receive. If you sell qualifying shares two or more years later, you will need the information from the year of purchase to file correctly. Do not assume your broker will have it. Many do not.

What Comes Next

Next: Post 6, Should You Max Out Your ESPP? Now that you understand how the benefit works and how it is taxed, the final question is how much to contribute. We walk through the factors that make maxing out the right call for some people and the wrong call for others, and how to think about your ESPP within your broader financial plan.

When you sell your ESPP shares matters more than most people realize. The timing alone can change how your gains are taxed and how much you actually keep.

When you sell your ESPP shares matters more than most people realize. The timing of your sale relative to your purchase date and your original enrollment date determines whether your gains are taxed as ordinary income or at the lower long-term capital gains rate. This distinction can have a significant impact on your equity compensation tax picture.

This post explains the two types of ESPP dispositions, how each is taxed, and what most people accidentally do without understanding the consequences.

What a Disposition Is

In the context of your ESPP, a disposition is any event that transfers your ownership of the shares. This includes selling them, gifting them, or otherwise transferring them. A sale is the most common disposition, and it is what we will focus on here.

There are two types of ESPP sales, based on how long you held the shares before selling: qualifying dispositions and disqualifying dispositions.

Qualifying Disposition

A qualifying disposition happens when you sell your ESPP shares after meeting both of the following holding period requirements:

You held the shares for more than two years after the offering period start date, AND more than one year after the purchase date.

Both conditions must be true. If you meet both, the tax treatment is more favorable.

In a qualifying disposition, the discount portion of your gain is taxed as ordinary income in the year you sell. Any additional gain above that is taxed at long-term capital gains rates, which are typically lower than your ordinary income rate.

Disqualifying Disposition

A disqualifying disposition happens when you sell before meeting either or both of the holding period requirements above. The most common version is selling the shares shortly after they are purchased.

In a disqualifying disposition, the entire discount, meaning the difference between the price you paid and the fair market value on the purchase date, is treated as ordinary income in the year you sell the shares. Any remaining gain or loss after that is a separate capital gain or loss, short-term or long-term depending on how long you held the shares after purchase.

Where the Confusion Comes From

Most employees who sell ESPP shares immediately after purchase are making a disqualifying disposition. This is extremely common. The shares hit the account, the gain looks attractive, and the natural instinct is to capture it. There is nothing wrong with this choice. In many cases, it is the most practical one. But many people make it without knowing it is a disqualifying disposition, and then they are surprised at tax time when ordinary income shows up on their W-2.

The second source of confusion is that the ordinary income from a disqualifying disposition is reported on your W-2, not just on a 1099-B from your broker. Your employer is required to add the spread to your wages in the year you sell the shares. If you are not expecting this, you may undercount your income for the year and underpay your taxes. Most employers do not withhold taxes on ESPP income the way they do on salary, so there is often a gap between what was withheld and what you actually owe.

We cover the 1099-B and W-2 reporting in detail in Post 5. It is one of the most mistake-prone areas in all of equity compensation taxation, and it is worth spending time on.

Which Is Better: Qualifying or Disqualifying?

It depends on your situation, and it is not always obvious.

A qualifying disposition gives you lower tax rates on more of your gain, which is generally better, but only if the stock actually stays at or above your purchase price for the two years you are holding. If the stock drops significantly after your purchase date, waiting for a qualifying disposition could cost you more in unrealized losses than you saved in taxes.

A disqualifying disposition via immediate sale locks in the discount gain right away and eliminates the risk of the stock declining. You pay ordinary income rates on the spread, but you lock in the gain and remove the risk of the stock dropping. There is nothing wrong with this choice. In many cases, it is the most practical one.

Most people focus on taxes here, but the bigger decision is balancing taxes with risk. The right answer depends on your tax bracket, your view of the stock, your overall financial situation, and how much concentration risk you already carry in your employer’s stock. This is exactly the kind of decision where working through the numbers with a financial planner is worth the time.

What Comes Next

Next: Post 5, Your ESPP and Your 1099. This is where the paperwork gets complicated. Your broker reports ESPP share sales on a 1099-B, but the cost basis is often reported incorrectly. If you file using the number your broker provides without adjusting it, you will likely overpay your taxes. We will show you exactly what to look for and how to fix it.

The discount is just the starting point. Here is how the lookback provision amplifies it and what that means for your decision to participate.

The discount is why people enroll in an ESPP. But understanding how that discount is calculated, and what a lookback provision adds to it, is what separates employees who maximize this equity compensation benefit from those who leave real money on the table.

This post covers how the purchase price discount works, what a lookback provision is, how the two combine to give you the best available price, and what that means in dollar terms.

The Basic Discount

Most ESPP plans offer a discount of 15% off the market price of the stock. This is the maximum the IRS allows for this type of plan. Some companies offer the full 15%. Others offer less. Your plan documents will state the exact percentage that applies to you.

What this means in practice: if your company’s stock is trading at $100 on the purchase date and your plan offers a 15% discount, you pay $85 per share. You immediately own an asset worth $100 that you paid $85 for.

That kind of built-in advantage is rare. You are not predicting the stock. You are not timing the market. You are simply buying an asset below its current market value.

What a Lookback Provision Is

A lookback provision gives you a better purchase price by letting the plan look back to the start of the offering period when calculating your discount.

Without a lookback, your discount is applied to the stock price on the purchase date only. With a lookback, the discount is applied to whichever price is lower: the price at the start of the offering period, or the price at the end.

This matters because:

If the stock went up during the offering period, the lookback locks in the lower starting price as your basis. You still benefit from the full price increase, and your discount is calculated on the cheaper starting price, not the higher ending one.

If the stock went down, the purchase date price is now the lower one, so that is what the discount applies to. Either way, you are always getting the discount on the better of the two prices.

An Example With Real Numbers

The table below shows how the lookback changes your outcome depending on whether the stock goes up or down during a 6-month offering period. In both cases, the plan offers a 15% discount.

In the upside scenario, the lookback turns a 15% discount into an effective 32% discount off the current market price. In the downside scenario, you still buy at a meaningful discount to where the stock actually is.

What This Means for Your Decision to Participate

If your plan includes both a discount and a lookback provision, the structure works in your favor in a rising market and still provides a built-in discount in a flat or declining one.

It is worth noting that if the stock falls significantly during the offering period and you hold the shares after purchase, you could experience losses beyond the discount. If you choose to sell shortly after purchase, you remove the ongoing market risk and capture the discount gain at that point in time. We will cover the sell versus hold decision in depth in Post 4, since the timing also has tax implications.

How much to contribute ultimately depends on your cash flow and your broader financial picture. We cover that in full in Post 6.

What Comes Next

Next: Post 4, Qualifying vs. Disqualifying Dispositions. This is the tax post. Once you own ESPP shares, when and how you sell determines whether your gains are taxed as ordinary income or at the lower capital gains rate. Most people accidentally do the worse thing. We are going to make sure you do not.

You opted in to your ESPP. Here is exactly what happens between enrollment and the purchase date and what you need to know to make the most of it.

You decided to participate in your company’s ESPP. Now what? The enrollment process seems simple on the surface. You pick a contribution percentage and submit. But there is a lot happening underneath that choice, and understanding it gives you more control over how this equity compensation benefit works for you.

This post covers how ESPP enrollment works, what an offering period is, how your contributions accumulate, what limits apply, and what to do if your situation changes before the purchase date.

The Enrollment Window

Most companies open ESPP enrollment twice a year, though some do it quarterly or once annually. The window is typically short, often two to four weeks. If you miss it, you generally have to wait until the next one. There is no catch-up option.

During enrollment, you do two things: you opt in to participate, and you choose your contribution rate. The contribution rate is the percentage of each paycheck that will be deducted and held in your ESPP account. Most plans allow contributions between 1% and 15% of eligible compensation. There is also an IRS limit to be aware of. Under a qualified ESPP, you can purchase up to $25,000 of stock per calendar year. More on how this works in the IRS Contribution Limit section below.

Your eligible compensation is usually your base salary. Bonus income, RSU vesting events, and commissions may or may not be included depending on your plan. Check your plan documents to confirm what counts.

What an Offering Period Is

The offering period is the span of time between when you enroll and when shares are purchased. During this time, contributions are deducted from your paycheck and accumulate for future stock purchases. The most common offering period length is 6 months.

Some companies use a simple structure: one offering period with a single purchase date at the end. Others use a longer offering period with multiple purchase dates built into it.

In longer plans, you may also see what is often referred to as an overlapping or “evergreen” structure. In these designs, a new offering period begins at regular intervals, even while prior offering periods are still ongoing. This means you can be participating in multiple offering periods at the same time, each with its own start date and potential lookback price.

Understanding the length and structure of your offering period matters because it determines how long your cash is tied up, when shares are purchased, and how the lookback provision is applied.

How Your Contributions Accumulate

Each pay period, the percentage you selected is withheld from your paycheck and moved into a non-interest-bearing ESPP account held by your employer or their plan administrator. The money sits there throughout the offering period. It is not invested in anything. It does not earn returns. It simply accumulates until the purchase date.

On the purchase date, the total accumulated amount is used to buy shares at the discounted price. Any leftover funds, because fractional shares typically are not purchased, are returned to your next paycheck.

The IRS Contribution Limit

The IRS limits ESPP participants to purchasing no more than $25,000 worth of stock per calendar year, measured based on the stock price at the beginning of each offering period. This is a statutory limit that applies across all Section 423 plans, regardless of what your specific plan allows.

In practice, this limit most often affects employees at high compensation levels who elect the maximum contribution percentage. If your base salary is high and your contribution rate is high, your plan administrator will automatically stop contributions once you approach the limit. It is worth understanding where you stand so this does not come as a surprise mid-period.

What Happens If You Need to Change or Stop Contributions

Most ESPP plans allow you to decrease your contribution rate or stop contributions entirely at any point during the offering period. The rules on increasing your contribution rate vary by plan. Many only allow increases during a formal enrollment window.

If you withdraw from the plan mid-period, your accumulated contributions are returned to you. You do not receive shares for that period. Some plans treat a withdrawal as a full cancellation and require you to wait until the next enrollment window to re-enroll.

Life happens. If a financial need comes up, it is better to pause contributions than to stretch yourself thin. But do this with full knowledge of your plan’s re-enrollment rules so you are not accidentally locked out longer than you expected.

What Comes Next

Next: Post 3, The ESPP Discount and Lookback Provision. This is where the math gets interesting. We break down exactly how the purchase price discount is calculated, what a lookback provision is, and why it can turn a 15% discount into something even more powerful in a rising market.

What is an ESPP, and why does it matter? ESPPs are one of the most underused benefits in tech compensation. This post breaks down exactly how they work and why they are worth paying attention to.

If you work in tech, you have probably seen ESPP in your benefits enrollment portal. Maybe you clicked past it. Maybe you signed up without fully understanding what you signed up for. Maybe you have been contributing for years and still feel fuzzy on how the whole thing actually works.

This post is the foundation of our ESPP series. We are going to cover what an ESPP is, how it works, why it is worth understanding, and what makes it different from the other equity compensation benefits for women in tech you likely have.

What Is an ESPP?

ESPP stands for Employee Stock Purchase Plan. It is a benefit that lets you buy your company’s stock at a discount, using money deducted from your paycheck over a set period of time. At the end of that period, the accumulated money is used to purchase shares for you, typically at a price lower than what the stock is trading for.

That discount is the core of what makes an ESPP valuable. You are buying an asset for less than it is worth the moment you receive it. Many companies offer a discount of 15%, though some offer less. The exact discount is specified in your plan documents.

How an ESPP Works, Step by Step

Here is the basic lifecycle of a typical ESPP:

Enrollment window. Your employer opens enrollment for a limited period, usually twice a year. During this window, you decide whether to participate and what percentage of your paycheck to contribute. If you miss the window, you typically have to wait until the next one.

Offering period. Once enrolled, your contributions are deducted from each paycheck over a defined period, often six months or one year. The money accumulates in an account but has not purchased any stock yet.

Purchase date. At the end of the offering period, your accumulated contributions are used to purchase company stock at a discounted price. The discount is calculated based on the stock price, sometimes using a lookback to give you the most favorable pricing available.

Post-purchase decision. Once the shares land in your account, you decide what to do with them. You can sell immediately, hold them, or do something in between. Each path has different tax consequences, which we cover in depth in Posts 4 and 5.

What Makes an ESPP Different From RSUs

If you also have RSUs, it helps to understand how these two benefits relate to each other.

RSUs are given to you. You do not pay for them. They vest over time, and on each vest date, the full value of the shares is taxable income to you. You did not put any of your own money in. You are receiving compensation in the form of stock.

An ESPP works differently. You are using your own money, deducted from your paycheck, to purchase shares. The benefit is the discount on the purchase price. Because you are using after-tax dollars to buy the shares, the tax treatment is also different, and more nuanced, than RSUs.

Both are valuable. But they work differently, and they require different decisions.

Why Most People Do Not Fully Use Their ESPP

The most common reason is that it feels complicated. The enrollment windows are short. The terminology, offering periods, purchase dates, lookback provisions, qualifying dispositions, is not exactly straightforward to understand. And because the shares are not automatically delivered the way RSU shares are, it is easy to treat the whole program as optional noise.

The second reason is concern about tying up cash. Contributing to an ESPP means a portion of your paycheck goes into an account you cannot access until the purchase date. For someone managing student loans, a mortgage, or other financial goals, that trade-off deserves real consideration.

But here is what gets lost in that calculus: the discount is guaranteed at the time of purchase. You are not betting on the stock going up to make money. You are buying an asset at below-market value. That is a different kind of opportunity than most investments.

What Comes Next in This Series

Next: Post 2, How ESPP Enrollment and Offering Periods Work. We break down the enrollment process, what happens to your money during the offering period, how contribution limits work, and what to do if your financial situation changes mid-period.