Co-Founder Agreement Essentials

A co-founder agreement is a contract between the founders of a business. It sets the basic rules for how you will own, run, and protect the company together. If you are forming a limited liability company, an LLC is a business structure that can protect the owners from some business debts and lawsuits, and the co-founder terms are often built into or attached to the operating agreement, which is the main internal document that explains how the LLC is owned and managed. If you are forming a corporation, the founders may use a separate founders' agreement along with corporate documents.

This agreement usually covers:
- who owns what percentage of the business
- who is expected to do which work
- how big decisions are made
- what happens if a founder quits, dies, becomes disabled, or stops contributing
- who owns the company's code, brand, customer lists, and other work product
- when and how founders can sell their shares or membership interests
- how disputes will be handled

Many founders skip this step because the relationship feels strong at the start. That is common, but it is also when expectations are least tested. A plain written agreement can reduce misunderstanding without changing the relationship.

A co-founder agreement is different from state filing paperwork. For example, articles of organization are the document filed with a state to create an LLC, usually with the Secretary of State. They do not usually explain founder roles, vesting, or exit rules in enough detail. You can learn more about startup formation in How to Form an LLC in the US and LLC vs. Corporation: Which Is Right.

This guide is general educational information, not legal advice, and it does not create an attorney-client relationship. Rules and best practices can depend on your state, tax plan, and business model.

The first big question is usually the ownership split. Some founders divide ownership 50/50 because it feels fair. Sometimes that works. Sometimes it creates deadlock if both founders disagree and there is no tie-break rule.

Your split should reflect real factors, such as:
- who is contributing cash at the start
- who is working full time versus part time
- who is bringing existing intellectual property or customer relationships
- who is taking lower pay for a longer period
- who is expected to keep building the business after launch

If you form a corporation, ownership is usually called stock or shares. If you form an LLC, ownership is usually called membership interests or percentage interests. Either way, the practical issue is the same: who owns how much, and under what conditions.

A smart place to focus is vesting. Vesting means a founder earns ownership over time instead of owning all of it on day one. A common example is four-year vesting with a one-year cliff. That means the founder earns nothing if they leave before one year, then a chunk becomes earned at the one-year mark, with the rest earned gradually after that. This is common because it helps prevent a person from walking away early with a large part of the company.

Example:
1. Two founders agree on a 60/40 split.
2. Both interests vest over four years.
3. Founder A leaves after eight months.
4. Under a one-year cliff, Founder A may leave with none of the unearned equity, depending on the agreement structure and state law.

You should also address whether money invested by a founder is treated as:
- a capital contribution, meaning money put in for ownership value, or
- a loan that the company may repay later

If these points are not clear, founders often end up arguing about whether they were equal partners, employees, lenders, or all three. A lawyer can help fit the ownership terms into the right structure. If you need help comparing entity choices first, see LLC vs. Corporation: Which Is Right.

A good co-founder agreement should say what each founder is actually expected to do. Titles alone are not enough. "CEO" and "CTO" may sound clear, but they often do not answer practical questions like who approves spending, who manages hiring, and who talks to investors or customers.

Write down:
- each founder's role and main responsibilities
- expected weekly time commitment
- whether anyone can keep another full-time job
- whether founders will receive salary now, later, or only after revenue or funding
- expense reimbursement rules
- who can sign contracts

Decision-making rules matter just as much as ownership. You should identify which decisions can be made by one founder and which require all founders to approve. Common examples of unanimous approval include:
- issuing new equity
- borrowing money above a set amount
- selling major company assets
- changing the business structure
- admitting a new co-founder or investor
- closing the business

For day-to-day issues, majority approval may be enough. For major issues, unanimous approval may make more sense. The right rule depends on the business and the number of founders.

If your company will sign customer or vendor deals, define contract authority early. An MSA, or master services agreement, is a contract that sets the general legal terms for an ongoing business relationship, often before specific projects begin. An NDA, or non-disclosure agreement, is a contract where one or both sides agree to protect confidential information. If one founder can sign either of these alone, the agreement should say so clearly. You can learn more about business contracts at Contracts and Agreements.

This section should also address deadlock. Deadlock means the founders cannot agree and the business cannot move forward. You may choose a tie-break process, such as mediation first, then a buyout process, or a designated outside adviser for limited issues.

Many co-founder disputes start here. Someone loses interest, moves away, gets sick, takes a new job, or stops doing the agreed work. If your agreement does not explain what happens next, the remaining founders may be stuck with an inactive owner who still controls a large share of the company.

Your agreement should cover several departure situations:
- voluntary resignation
- termination for poor performance or misconduct
- disability or death
- long-term failure to meet time or work commitments
- divorce, bankruptcy, or personal creditor issues that could affect ownership

Important questions include:
- Does the company have the right to buy back some or all of the departing founder's equity?
- Is the buyback price based on fair market value, original cost, or a formula?
- Does the price change if the founder was fired for cause?
- What happens to unvested equity?
- Can the departing founder keep using company information, code, branding, or customer contacts?

You should also address restrictions carefully. Some agreements limit a founder's ability to compete, solicit employees, or solicit customers after leaving. These rules are heavily state-dependent, and some states restrict or disfavor certain non-compete terms. That is one reason a licensed attorney is worth involving.

A practical point: if one founder created software, designs, course materials, or branding before the company existed, the agreement should say whether that property is being licensed to the company or fully assigned to it. Without that language, the business may not clearly own a core asset.

If you are building with a friend or family member, this section can feel awkward. It is still better to discuss it early. The conversation is usually less stressful before anyone is upset.

A startup's most valuable assets are often not physical. They may be software code, a product design, a brand name, a website, a process, a course, or a customer list. Your co-founder agreement should say who owns those assets and what each founder must do to transfer ownership to the company when appropriate.

Key concepts to cover:
- assignment of inventions, code, designs, and other work product to the company
- confidentiality duties during and after the founder relationship
- rules for using open-source software or third-party materials
- trademark and brand ownership
- social media account control
- domain name ownership

If you plan to use a brand name, check official federal trademark records at USPTO.gov. A trademark search can help you avoid building under a name that may conflict with someone else's rights.

If you want to use another business name publicly, that may involve a DBA, which means "doing business as" and is a registered trade name used instead of the company's legal name. DBA rules are set by state or local agencies, and a DBA does not create a separate legal entity.

For confidentiality, founders often use an NDA, but the core confidentiality promises may also be placed directly inside the co-founder agreement. The important part is being specific about what is confidential, how it can be used, and what happens when someone leaves.

Some companies may also have federal reporting duties. A BOI report is a beneficial ownership information report, a federal filing that may require certain companies to report information about the people who own or control them. BOI reporting rules have changed over time, so always confirm current requirements through official federal sources and a licensed attorney. For broader legal setup help, see Business Compliance and Licensing.

You do not need a perfect document on day one, but you do need a serious conversation. A useful process looks like this:

1. List the hard topics before filing the business: ownership, roles, money, vesting, exits, voting, and IP ownership.
2. Write down each founder's expectations in plain language.
3. Compare your business structure options. If needed, review How to Form an LLC in the US and What Is an EIN and How to Get One. An EIN, or Employer Identification Number, is the business tax ID issued by the IRS.
4. Decide what belongs in the co-founder agreement and what should also appear in the LLC operating agreement or corporate documents.
5. Have a licensed attorney review the draft before everyone signs.
6. Keep signed copies and update the agreement when the business changes.

You may also need a registered agent, which is the person or company authorized to receive legal and government papers for the business. This is usually part of entity formation, not the co-founder agreement itself, but founders should know who is responsible for keeping state records current.

Legal costs vary by state, complexity, and whether you are starting from scratch or revising a bad draft. For a founder agreement review or a set of formation documents, small-business legal fees often fall into state-dependent flat-fee ranges from a few hundred dollars to a few thousand dollars. Those ranges are not quotes. If there are tax issues, IP transfers, multiple entities, or investor-readiness work, the total can be higher.

If you want a better sense of legal pricing, see How Much Does a Business Lawyer Cost. If you want help finding a lawyer, you can use FoundryCounsel's free matching service at Get Matched or learn more at How It Works. FoundryCounsel is not a law firm and does not provide legal advice. It offers general educational information and a free way to connect business owners with licensed attorneys.

When you ask for a match or contact a lawyer, share only basic contact details and a short description of the problem. Do not send sensitive personal identifiers, bank details, immigration information, or confidential business secrets through a form.