The wrong business partner is more expensive than no partner, because you cannot simply stop working with someone who owns half the company. The decision is worth treating as seriously as a large investment, and the single most useful test is whether the person brings something you do not have rather than more of what you already do.
Everything below is easier to settle while both of you still agree.
Complementary beats similar
Two founders with the same strengths produce a business with the same gaps. A technical founder pairing with someone who can sell covers more ground than two technical founders, however capable.
Be specific about what each person is responsible for. Partnerships where both people believe they run the same function generate conflict early and constantly.
Test before you commit
Work on something real together before agreeing to share ownership. A short paid project, a contract delivered jointly, or a defined piece of work tells you more than months of discussion.
What you are testing is how they behave under pressure, whether they do what they said by when they said, and how they handle disagreement. None of that appears in a conversation about vision.
Write it down while you agree
A shareholder agreement is what converts goodwill into something enforceable. It should cover what each person contributes in money, time and skill; how decisions are made and how deadlock is broken; what happens if someone wants out, stops contributing, becomes ill or dies; how the business is valued in those events; and who may buy the shares.
Consider vesting, so equity is earned over time rather than held in full from the first day by someone who may leave in month three.
Ownership split is not automatically equal
An even split is common and frequently wrong, because contributions in capital, time and risk are rarely equal. Deciding it deliberately at the start is far easier than renegotiating it once resentment has formed.
Keep a securities register recording who holds what. It is a legal requirement and it is the document a funder or buyer will ask to see. The entity itself is registered with the Companies and Intellectual Property Commission.
Partnerships with companies are different
A supply, distribution or joint venture arrangement with a larger company is a contract rather than co-ownership, and the questions change: exclusivity, minimum volumes, payment terms, who owns anything created jointly, and how either side ends it.
Read what happens on termination before signing. A business built entirely around one corporate partner is one decision away from having no customers.
Frequently asked questions
What makes a good business partner?
Skills and access you do not have, clearly separated responsibilities, and demonstrated reliability under pressure rather than shared enthusiasm.
How do I test someone before committing?
Deliver a real piece of work together. How they handle deadlines, pressure and disagreement is what you are assessing.
Should ownership be split equally?
Not automatically. Contributions in capital, time and risk are rarely equal, and deciding deliberately upfront is far easier than renegotiating later.
What must a shareholder agreement cover?
Contributions, decision-making, deadlock, what happens if someone exits or dies, how the business is valued, and who may buy the shares.
What is vesting and why use it?
Equity earned over time rather than granted in full immediately, so a founder who leaves early does not retain a full stake.
Further reading
Originally published in September 2018. Updated September 2026 into guidance on choosing and structuring a business partnership.
