How to split equity in a startup

Splitting equity among co-founders can be a complicated process. It's important to take the time to hash out the details in order to avoid misunderstandings, reward work fairly, and operate your startup in a way that your team is comfortable with.

In this article, we’ll cover the basic factors to consider when discussing how to divide equity in a startup — including the process of dividing equity among founders — as well as common pitfalls to avoid.

When it comes to splitting equity among founders, an even split might sound like the most logical option. That said, there are number of additional factors tp consider that might influence how you choose to split your company's equity.

1. Experience and expertise

An important factor you might consider when dividing equity is a founder's expertise — including the years of experience they have in the industry or related industries — and the skills they bring to the table.

Let’s say you’re starting a health insurance technology company. If a member of the founding team has worked at a major health insurance firm for several years, they might have unique insights about the future of the industry. Perhaps these insights have a significant impact on who you approach as prospective clients, where you target marketing efforts, or simply on your company's overall strategy. In a case like this, you might decide that this founder deserves a higher share of the equity.

However, it’s important to remember that expertise isn’t a totally obvious reason to give a founder more equity. Let’s say another founder has never worked in insurance but has been involved in a personal situation that has led her to research the health insurance landscape in depth. As a result, she might have a better idea of what customers are looking for and might bring new ideas, creative approaches, and out-of-the-box solutions to the table.

2. Capital investment

Founders contribute two common types of capital to a venture: monetary capital and sweat equity. Monetary capital means that a founder has contributed cash to help kickstart and grow a business. It’s fairly straightforward to calculate the value that monetary capital adds to a business.

Sweat equity is a little more difficult to define, although it can be equally as important. Generally speaking, sweat equity refers to labor and time invested into the company. Consider these questions:

• How many hours is a founder investing into the company in a given week, month, or quarter?
• Are their contributions something that no one else — or only a few others in the company — can offer?
• Can you establish metrics to track their sweat equity?

One way to determine the worth of sweat equity is to assign a founder’s hourly rate to the various roles and duties they occupy. Another method is to establish a flat rate and track progress by project milestones. This metric can be especially useful when calculating equity for founders offering both capital and sweat equity.

3. Level of involvement

Some founders like to get involved in the daily operations of a company, like managing the product development team. This can impact the amount of equity they receive.

Let's say a co-founder was closely involved with the product from the get-go. They helped set the product’s vision, built out its roadmap, and hired the initial team to execute these plans. In that case, they might get a larger share of equity than a co-founder who was away from the company for the first year and contributed to the product later on.

4. Ideas and intellectual property

It’s often assumed that the founder who came up with the original idea behind the business deserves the larger share of equity, but that's not necessarily the case. An idea that isn’t executed never goes anywhere. If another founder has contributed a valuable skill set that actually gets the company off the ground, their contributions might be just as important.

Of course, if a founder is bringing ideas to your company that they developed on their own or at a previous venture, these ideas can be considered intellectual property. Intellectual property is an important factor to consider when determining what a fair equity split will look like.

5. Salary and other compensation

Often a founder will take a smaller salary — or no salary at all — in exchange for more equity. A founder may also take a larger salary with less equity for a few months, then shift to receiving only equity. Whatever the arrangement is, hone in on a formula that feels fair and is agreed upon by all founders. Then, stick to it.

Note: Most founding teams combine methods — for example, agreeing on a weighted or role-based split that is then subject to a standard 4-year vesting schedule. No single method is universally right.

Keep your cap table clean from day one.

However you split equity, the agreement is only as useful as your ability to track it accurately over time. Cap table management software makes it easy to record founder equity, model dilution from future funding rounds, issue stock options to employees, and stay investor-ready at every stage.

Mercury's Software Stack includes recommended cap table tools used by founders at every stage. Popular options include:

• Carta — industry standard for VC-backed startups; handles equity, 409A valuations, and compliance
• Pulley — founder-friendly, lower cost, strong for early-stage companies
• Cake Equity — flexible and internationally friendly; good for global teams
• Capsign — simple cap table management for pre-seed and seed-stage startups

Starting with proper cap table software early avoids the messy and expensive process of reconstructing equity records before a funding round or acquisition.

In a dynamic equity split, the amount of equity each co-founder gets depends on the amount of capital or time they invest into the company. That amount resets monthly and there's a predetermined formula used to decide how the equity should be doled out.

Businesses are often works in progress. As a company's direction, needs, and goals evolve, the roles and depth of involvement of each founder will change too. A dynamic equity split recognizes these shifts and allows founders to split shares according to the value that they add to the company at any given time.

Equity changes fast — your cap table software should keep up.

Every time you issue options to an employee, close a funding round, or bring on a new co-founder, your cap table needs to reflect it accurately. Mercury's Software Stack includes cap table tools vetted for founders at different stages, from pre-seed to Series B and beyond. Explore the full list and see what other Mercury customers use to manage their equity.

You may be familiar with a vesting schedule if you’ve ever worked for an employer that offered vesting schedules for retirement contributions or other company benefits.

An equity vesting schedule works similarly. It lays out a timeline for founders to commit to their involvement in the company and ensures they don't walk away from the company too early.

An example timeframe for an equity vesting schedule is four years. After a year, a founder is entitled to 25% of their equity. This first portion is known as the cliff. Once they hit the four-year mark, they can swoop into 100% of their equity. A common caveat is that the founder receives no equity if they split before the one-year mark.

Another way to slice it: Each founder gets 25% after a year of involvement in the company, and the remaining 75% can be doled out in 25% chunks at the end of each year for the following three years.

Although each situation is unique, there are a few common stumbling blocks founders encounter when deciding on startup equity splits.

• Making assumptions: Assuming one founder is entitled to a certain share of equity because of a certain contribution — for example, if the founder came up with the idea for the company — can lead to disagreements down the road. Keep your assumptions in check by talking things out and be cognizant of the fact that each founder weighs contributions differently. Try to create a metric upon which all founders can be measured equally. 
• Not getting it in writing: You'll want to make sure that the equity split you decided on is spelled out in a written agreement. A seasoned attorney who specializes in startups can help you lay out terms, address everyone’s concerns, and inform you of any potential issues that might pop up. 
• Mixing business with friendship: There’s nothing wrong with starting a company with friends, former colleagues, family, or significant others, but don’t let the external factors in these relationships cloud your judgment. Be as objective as possible when negotiating for equity. ‍
• Being hasty in your decision-making: Deciding how to split equity is a major decision and it can often be permanent. Act in haste and you run the risk of making a decision that you’ll regret. Take a step back, make sure you have all the information you need, and play around with different scenarios and equity splits before making a decision.

Let's walk through the process for how equity deals are reached.

1. Start with a discussion

Before you make formal decisions, hash things out verbally with your co-founders. There are many details that might not be easy to get down on paper and carving out time to talk lets you air your concerns and better understand each founder's perspective. Investing the time to have these discussions comes with another benefit: It shows members that their opinions are valued.
The discussion phase is also the best time to figure out if and how to divide equity to startup founders, advisors, and employees. Flesh out details like whether only full-time employees will be eligible to get equity, how much each employee will receive, what their roles and duties are, and what milestones they need to hit to earn their share of the equity.

2. Negotiate

Once all founders have had a chance to air their concerns verbally, it's time to put on your negotiation caps and decide how equity will be split up.

If you're feeling stumped about how to iron things out, consider using one of the many founder equity calculators available for free on the internet. These calculators can provide numbers that can help you figure out what to factor in when negotiating.

3. Put it in writing

Now that you have the terms hashed out, it’s time to create a founders' agreement. This legal contract will cover the various equity splits and can be referred to as the company grows.

It’s also your source of truth. From the start, all agreed-upon terms should be outlined in this agreement. This ensures that the best interests of all parties are protected. And if you feel that these terms might change as the company evolves, you can add a clause indicating that certain terms will be reassessed on a monthly or yearly basis.

Should co-founders split equity 50/50? For most founding teams, an equal or near-equal split is the right starting point — and it's what Y Combinator and most experienced investors recommend. The reasoning is straightforward: it takes 7–10 years to build a company of real value, and small differences in early contributions don't justify large differences in long-term equity. A dramatically unequal split can signal to investors that the founding team isn't aligned, reduce motivation for the lower-equity co-founder, and create resentment that compounds over time.

That said, 50/50 is not always the answer. If one founder is clearly more committed — working full-time while the other is part-time, for example — a modest difference like 60/40 may be more appropriate. The key is to pair whatever split you choose with a proper vesting schedule, which protects everyone if the arrangement doesn't work out. The split itself matters less than the honesty and alignment of the conversation that leads to it.

How do you split equity with no revenue? At pre-revenue stage, equity splits should be based on forward-looking commitment and contribution rather than historical results — because there are no results yet. The most important factors to weigh are: who is working full-time vs. part-time, who is bringing in critical IP or domain expertise, who contributed initial capital or funding, and what each founder's long-term role in the company will be.

At this stage, a dynamic equity model like Slicing Pie can be useful because it accrues equity in real time based on actual inputs rather than guesses. Alternatively, many pre-revenue teams default to an equal split with a 4-year vesting schedule, which gives the company the flexibility to course-correct early if someone's commitment changes. Whatever you decide, document it formally in a founders' agreement before any meaningful work begins.

What if one founder leaves? This is exactly what vesting schedules are designed to handle. The standard startup vesting structure is four years with a one-year cliff: if a founder leaves within the first year, they receive no equity; after the cliff, they vest 25% of their shares, with the remaining 75% vesting monthly over the following three years.

When a founder departs, unvested shares typically return to the company's equity pool, which can then be reissued to a replacement hire, employees, or reserved for future rounds. If a founder leaves after the cliff but before full vesting, they keep what they've earned, and the rest reverts. 

Having a vesting schedule in place — and ideally a buyback clause for unvested shares — is the single most important protection against a "dead equity" scenario where a departed founder still owns a large chunk of the company. Without vesting, this is one of the most common and most damaging cap table problems investors encounter.

How does founder equity affect future fundraising rounds? Investor decisions are heavily influenced by your cap table. Here's what they look at and why it matters:

First, a heavily fragmented or unequal cap table can raise red flags. If a non-active founder holds 30% of the company, investors may question whether that person can be a drag on decision-making — or worse, a blocker during an acquisition.

Second, every funding round dilutes existing shareholders, including founders. A seed round might dilute founders by 15–25%; a Series A by another 15–20%. Founders who started with 50/50 might each own 20–25% by Series A, which is still considered healthy. Understanding this dilution math up front helps you plan how much equity to retain and how aggressively to raise.

Third, investors evaluate alignment. If the founding team's equity structure suggests strong incentives and long-term commitment, it de-risks the investment. If it looks messy or contentious, it becomes a negotiating point or a dealbreaker. Tools like Carta or Pulley (part of Mercury's Software Stack) make it easy to model dilution scenarios before you sign a term sheet.

What tax implications should founders consider when issuing equity? This is one of the most consequential — and most commonly overlooked — areas of founder equity. There are three key things every founder should understand:

The 83(b) Election

When you receive restricted stock subject to a vesting schedule, the IRS default is to tax you on the fair market value of each batch of shares as they vest — which could mean a large tax bill in years two, three, and four as the company's value grows. Filing an 83(b) election within 30 days of receiving your equity grants tells the IRS that you want to be taxed immediately on the current value instead. Since founder shares are typically issued when the company is worth nearly nothing, the tax is minimal — and any future appreciation is taxed at the lower long-term capital gains rate rather than ordinary income rates (up to 37%). Missing the 30-day window is an irreversible mistake that can cost founders hundreds of thousands of dollars.

Qualified Small Business Stock (QSBS) — Section 1202

If your company is a qualified C-corporation and you hold your shares for at least five years, you may be eligible to exclude up to $10 million (or 10x your cost basis, whichever is greater) in capital gains from federal taxes entirely when you sell. QSBS is one of the most valuable tax benefits available to startup founders, but it comes with specific eligibility requirements — including the type of business, the size of the company at the time of issuance, and how the stock was acquired. Filing an 83(b) election also starts your QSBS holding period clock earlier, which is another reason to file it immediately upon grant.

Capital Gains Holding Periods 

Shares held for more than one year qualify for long-term capital gains rates (currently 0%, 15%, or 20% depending on income), which are significantly lower than ordinary income rates. If you sell before one year, gains are taxed as ordinary income. Planning your equity timing around these thresholds — especially at exit — can make a material difference in your after-tax proceeds.

Always consult a startup-experienced tax advisor or attorney before issuing equity. The decisions you make in the first 30 days of founding can have multi-million-dollar tax consequences years later.

Don't rush the process of figuring out how to split equity. If you strike the right balance, you can help ensure that your co-founders feel rewarded for their work and stick around for the long run.