A great co-founder relationship can make a shareholders agreement feel unnecessary. You trust each other, you are moving quickly, and there are far more urgent jobs on the list. But who needs a shareholders agreement? In practice, almost any Australian startup with more than one shareholder does – particularly where the business, the shareholding, or the stakes are likely to change.

A shareholders agreement is not a document you prepare because you expect a fight. It is a practical set of rules agreed while everyone is aligned, so decisions do not get stuck and difficult conversations do not have to be negotiated from scratch under pressure.

Who needs a shareholders agreement?

If one person owns and operates a company, a shareholders agreement may add little value. The moment there are two or more shareholders, however, it becomes a seriously useful governance tool. That includes friends starting a side hustle, spouses building a family business, founders launching a venture-backed startup, and an established company bringing in an investor or key employee as an owner.

The need becomes more pressing when shareholders contribute different things. One founder might bring the original idea and work full-time; another may provide capital, industry contacts or technical expertise. Those contributions can all be valuable, but they do not automatically answer the hard questions: who can make which decisions, what happens if a founder stops contributing, and how can someone sell their shares?

A clear agreement gives those questions a home. It should work alongside the company constitution and the Corporations Act 2001, not replace them. The constitution governs the company broadly. A shareholders agreement is a private contract between the shareholders, allowing more tailored rules around ownership, conduct and decision-making.

The startup situations where it matters most

Every business with multiple owners can benefit, but some moments make an agreement close to essential.

Two or more founders are splitting equity

An equal split can look fair at day one. It can look very different six months later if one founder is working 60-hour weeks and the other has taken a full-time role elsewhere. Without an agreement, the departing founder may retain their entire stake, even if they are no longer helping to build the business.

Founder vesting, sometimes called reverse vesting, can address this. Shares are earned over time, usually with a period before any shares vest. If a founder leaves early, the company or remaining shareholders may have the right to buy back some or all of their unvested shares. The right structure depends on the circumstances, tax position and legal advice, but the commercial principle is simple: equity should reflect sustained contribution, not just a strong first meeting.

You are taking investment

Investors want to know who has control, how future shares can be issued and whether a minority shareholder can derail a future funding round or exit. A well-built agreement can set out investor rights without giving away more control than the founders intend.

This might include pre-emptive rights, which give existing shareholders the first opportunity to buy new shares before outsiders do. It may also cover information rights, board appointment rights and reserved matters – significant decisions that require shareholder approval.

The trade-off matters. Giving an investor a veto over routine operational choices can slow a startup down. The smarter approach is to reserve approval for genuinely material decisions, such as issuing shares, changing the business direction, taking on significant debt, selling major assets or winding up the company.

You are issuing equity to employees or advisers

Equity can be a smart way to attract people when cash is tight. It can also create a messy cap table if it is handled casually. Before issuing shares to a senior employee, adviser or contractor, founders should be clear about what that person receives, what happens if they leave, and whether they will have voting rights.

In many cases, an employee share option plan may be more suitable than issuing ordinary shares outright. Either way, your shareholders agreement should anticipate future equity incentives and set sensible transfer restrictions. You do not want former team members holding small parcels of shares with no clear pathway to sell them years later.

There is a real chance of a sale, merger or expansion

A company with a valuable growth plan needs a path to a clean transaction. Buyers do not enjoy negotiating with a scattered group of shareholders at the eleventh hour.

Drag-along and tag-along provisions are often used here. Drag-along rights can require minority shareholders to sell if an agreed majority accepts a genuine offer for the company. Tag-along rights protect minority shareholders by allowing them to join a sale on the same terms as a majority holder. Used together, these provisions can protect fairness while keeping an exit achievable.

You have a 50/50 ownership structure

A 50/50 split is common and can work brilliantly – until the founders disagree. If each shareholder has equal voting power and no agreed deadlock process, neither may be able to move the company forward.

A shareholders agreement can provide a staged path: good-faith discussion first, then mediation, and finally an agreed buy-sell mechanism if the deadlock cannot be resolved. The best mechanism depends on the people, funding capacity and business value. What matters is agreeing on the process while both parties still want the business to succeed together.

What a useful agreement should cover

A generic online template may identify the usual headings, but the value comes from tailoring the agreement to the way your business actually operates. The document should be commercially clear enough that founders can use it, not merely store it in a data room.

At a minimum, it should deal with ownership and voting rights, director appointments and board decisions, funding obligations, share transfers, founder departures, confidentiality and intellectual property. It should also address how profits may be distributed, whether shareholders can work in competing businesses, and how disputes will be managed.

For startups, a few issues deserve particular attention:

• Decision rights: Define which decisions directors can make and which need shareholder consent. Keep the reserved matters list focused, or every operational decision becomes a bottleneck.
• Future funding: Set expectations about capital calls, new share issues and dilution. A shareholder who cannot or will not contribute in a future round should understand what that means for their percentage ownership.
• Share sale rules: Include rights of first refusal or first offer, valuation methods and rules for transfers to family trusts or related entities where appropriate.
• Good leaver and bad leaver outcomes: Distinguish between a founder leaving because of illness or a mutually agreed change, and leaving after serious misconduct or a breach of obligations. These clauses need careful drafting because the financial consequences can be significant.
• IP ownership: Make sure intellectual property created by founders, employees and contractors is properly assigned to the company. The company cannot confidently raise capital or sell if the core code, brand or product design is owned personally by an individual.

When is the right time to put one in place?

Before shares are issued is ideal. At that point, the founders can decide on ownership, vesting and control without needing to unwind assumptions that have already hardened.

The next best time is before a major event: bringing in an investor, issuing employee equity, expanding overseas, appointing a new director, or signing a deal that materially changes the business. These are the moments when gaps in governance become expensive.

That said, it is never too late to improve the arrangement. Existing shareholders can enter into a new agreement, provided the process is managed properly and everyone has the chance to obtain independent legal advice. Expect the conversation to be more complex once the business has value, particularly if different shareholders have different views on valuation or control.

Common mistakes founders make

The biggest mistake is treating the agreement as a legal formality rather than a commercial operating manual. Founders may sign a document without discussing what they would actually do if someone leaves, a funding round dilutes the team, or an acquisition offer arrives.

Another is copying terms from a business with a completely different model. A bootstrapped consultancy, a SaaS startup seeking venture capital and a family-owned trading company may all have shareholders, but they need different rules around funding, employment, dividends and exits.

It is also risky to let legal and financial decisions run on separate tracks. The share structure in the agreement needs to match the company records, cap table, tax planning and financial model. If you are promising options, raising capital or planning an exit, those pieces need to line up from the start.

Make the agreement fit the business you are building

A shareholders agreement does not need to predict every challenge your company will face. It does need to establish how the people who own the company will make decisions when the pressure is on.

For founders, the real benefit is momentum. Everyone knows what they own, what they are responsible for and what happens if circumstances change. That clarity makes it easier to bring in capital, reward the right people and stay focused on building the business. At Startup Nerd, our legal, finance and growth specialists help founders make those moving parts work together, so governance supports the next stage rather than slowing it down.

The most useful time to have the difficult conversation is when it is still an easy one. Put the rules in place early, revisit them as the business grows, and give your future company a fairer, cleaner path forward.