Bringing on a co-founder is the most consequential contract most entrepreneurs sign, and it is the one they are least likely to write down. The conversation happens over beers. Somebody says fifty-fifty. Everybody nods. Eighteen months later one person has been working nights and weekends, the other took a job, and both of them still own half a company. There is no clean way out because nobody built one.
The fix is not complicated and it is not expensive. It is four documents and one honest conversation, handled at the beginning while everyone still likes each other.
What You Will Learn
- Why an equal split is a decision, not a default
- How vesting protects the person who stays
- The 83(b) election and the deadline that cannot be extended
- Why IP assignment matters more than the equity number
- Six mistakes founders make when bringing on a co-founder
- Which documents actually need to exist
The Split Is a Decision, Not a Default
Fifty-fifty feels fair because it avoids a hard conversation. It is also the split most likely to produce deadlock, because nobody can break a tie. If the company has two owners with equal votes and no tiebreaker, a disagreement about direction becomes a disagreement with no resolution mechanism short of litigation.
Before settling on a number, price the contributions honestly. Who had the idea, who is leaving a salary, who is funding the first year, who owns the customer relationships, and who is going to be doing the work in month thirty. Past contribution is worth less than future commitment, and most founder splits overweight the former.
Then decide governance separately from economics. Equal ownership with a designated decision-maker on operations is workable. Equal ownership with equal control and no tiebreaker is a coin flip on whether the company survives its first real disagreement. Our overview of the founder-led company legal map covers how these pieces fit together.
Vesting Is the Single Most Important Term
Vesting means equity is earned over time rather than owned outright on day one. The standard is four years with a one-year cliff: nothing vests for twelve months, then twenty-five percent vests at the cliff and the rest accrues monthly.
Founders resist this because it feels like distrust. It is the opposite. Vesting is the provision that protects whoever stays. If your co-founder leaves after five months, vesting means they leave with nothing rather than with half your company on the cap table forever, dead weight that every future investor will ask about and every future hire will resent.
Two terms deserve attention when bringing on a co-founder:
- Acceleration. Single-trigger acceleration vests equity on a sale. Double-trigger requires a sale plus a termination. Investors and acquirers strongly prefer double-trigger, and single-trigger can complicate an exit.
- Repurchase rights. The company should have the right to buy back unvested shares at cost, and the mechanics should be automatic rather than dependent on a board vote that a departing founder might sit on.
Related concepts are covered in our pieces on why the employee option pool is not free and on issuing equity for services.
The 83(b) Election and a Deadline You Cannot Miss
When a founder receives restricted stock subject to vesting, the tax code treats each vesting event as income at that moment, valued at the stock price then. If the company appreciates, that creates a growing tax bill on shares the founder cannot sell.
A Section 83(b) election flips this. The founder elects to recognize income at grant, when the shares are typically worth almost nothing, and all subsequent appreciation is treated as capital gain instead of ordinary income. On founder stock issued at formation, the tax at grant is often close to zero.
The election must be filed within 30 days of the transfer. That deadline is statutory and there is no relief for missing it. The IRS now provides a standardized form for the election, Form 15620, and an electronic filing path in addition to the traditional certified-mail route. Calendar the deadline the day the shares are issued, not the day you get around to it.
IP Assignment Matters More Than the Equity Number
A company that does not own its own intellectual property is not sellable and usually not fundable. Every founder must sign an agreement assigning to the company all work product created for the business, including code, designs, brand assets, and customer lists.
This matters most for the co-founder who is not yet full time. If someone is building your product on weekends while employed elsewhere, their employer may have a claim to that work depending on the state and the terms of their employment agreement. New York, for example, narrowed employer invention-assignment rights under Labor Law Section 203-f, but the carve-outs for work relating to the employer’s business remain broad. Diligence this before you build on top of it, not after a term sheet arrives.
Confidentiality belongs in the same package. Our guides on the non-disclosure agreement and on defining confidential information explain what these clauses need to say to be useful rather than decorative.
Six Mistakes Founders Make
- Nothing in writing. A verbal split is enforceable in theory and unprovable in practice. Memories diverge in exactly the direction each person’s interest points.
- No vesting. The mistake that most reliably kills a company, because it cannot be fixed once the other founder has left and refuses to sign anything.
- Missing the 83(b) window. Thirty days, no extensions, real tax consequences.
- No IP assignment. Discovered during diligence, at the worst possible moment, with the least possible leverage.
- Confusing equity with compensation. Ownership is not a salary substitute forever. Decide when cash compensation starts and what happens if it never does.
- No exit mechanism. Buy-sell provisions, valuation methodology, and transfer restrictions need to exist before somebody wants to leave, divorce, or die.
Founder disputes that reach litigation almost always trace back to one of these six. We have written separately about how New York founder disputes unfold when the documents are thin.
The Documents You Actually Need
Bringing on a co-founder properly requires four instruments, and none of them are long:
- The operating agreement or shareholders agreement. Governance, voting, deadlock resolution, transfer restrictions, and buy-sell terms. This is the company’s prenup, and we explain why in our piece on the operating agreement as prenup.
- Restricted stock purchase agreements or unit grant agreements. The vesting schedule, repurchase rights, and acceleration terms.
- Confidential information and invention assignment agreements. Signed by every founder, contractor, and employee, without exception.
- A clean cap table. Not a napkin. Our cap table primer covers what belongs in it.
Entity choice interacts with all of this. LLCs offer flexibility that suits bootstrapped businesses; C corporations suit companies planning to raise priced venture rounds and issue options. If outside money is on the horizon, review the SEC guidance on exempt offerings before you take a check from anyone.
Founders in regulated industries have an additional layer, because ownership changes may require regulator approval. Cannabis operators should review the ownership and control analysis at Cannabis Industry Lawyer, and operational readiness work is handled by our consulting affiliate Collateral Base. Disputes that have already escalated are handled by Howard Law Group.
Frequently Asked Questions
Is a fifty-fifty split ever the right answer when bringing on a co-founder?
Sometimes, when contributions and commitment are genuinely equal. The risk is not the economics but the governance. If you choose an equal split, build in a tiebreaker or a deadlock mechanism so a disagreement has a resolution path.
Can we add vesting after the fact?
Only by agreement of everyone affected, which is straightforward while relationships are good and nearly impossible once they are not. Adding vesting later can also carry tax consequences, so it should be reviewed before executing.
What happens if I miss the 83(b) deadline?
The election is unavailable for that grant. Income is then recognized as the shares vest, based on value at each vesting date. Founders in that position should discuss alternatives with tax counsel, since options depend on the specific facts.
Does my co-founder need to quit their job first?
Not necessarily, but their existing employment agreement should be reviewed for invention assignment, non-solicitation, and conflict-of-interest terms before they contribute work product to the new company.
Next Steps
If you are bringing on a co-founder in the next quarter, the paperwork should be done before the work starts, not after. Howard East sets up founder documents, vesting schedules, and governance terms for early-stage companies on a fixed-fee basis. Contact our team to get the structure right the first time.
This article is general information, not legal advice. No attorney-client relationship is created by reading it. Attorney Advertising.
