Shareholder agreements for UK startups: a practical guide

What is a shareholder agreement?

A shareholder agreement is a private contract between some or all of the shareholders in a company. It sets out how the company should be run, what shareholders can and cannot do, and what happens in specific situations such as a shareholder leaving, a dispute, or a sale of the business.

It works alongside your articles of association. The articles set out the basic rules for the company, while the shareholder agreement deals with the practical relationship between shareholders and fills the gaps the articles leave open.

Why your articles are not enough

Most UK startups are incorporated with the model articles from Companies House. These are fine for getting started but they are generic. They were not written for your specific business, your co-founder dynamics, or your plans to raise investment.

The model articles rarely cover issues like:

• What happens if two founders disagree on a major decision
• How a founder can sell their shares if they leave
• What happens if an investor wants to sell the whole company but a minority shareholder refuses

A shareholder agreement lets you tailor these rules to your situation. Unlike the articles, it is also private. You do not have to file it at Companies House, so you can include commercially sensitive details without making them public.

How a shareholder agreement differs from a founders' agreement

A founders' agreement typically covers the early relationship between co-founders: equity split, roles, IP assignment, and vesting. A shareholder agreement is broader. It governs the relationship between all shareholders, including any later investors, and it focuses on governance, share transfers, and decision making.

You may have both documents. The founders' agreement handles the early informal stage, while the shareholder agreement takes over once the company has multiple shareholders or takes outside investment.

When to put one in place

You do not need a shareholder agreement if you are the only shareholder. But as soon as you have more than one shareholder, even if it is just you and a co-founder, a simple agreement can prevent costly misunderstandings later.

Common trigger points include:

• Bringing on a second founder or issuing shares to an employee
• Taking your first outside investment
• One founder reducing their involvement or leaving
• Introducing an option scheme that changes the shareholding structure

Putting an agreement in place early, when everyone is still aligned, is easier than trying to negotiate one after a disagreement has started.

Key clauses to consider

Every agreement is different, but most early-stage UK startups should think about these areas.

Share transfer restrictions and pre-emption rights

This controls what happens when a shareholder wants to sell their shares. Pre-emption rights give the other shareholders the first option to buy the shares before they are offered to an outsider. This helps you keep control of who becomes a shareholder.

Drag-along and tag-along rights

Drag-along rights allow a majority shareholder to force minority shareholders to sell their shares if a buyer wants to buy the whole company. Tag-along rights protect minority shareholders by letting them join the sale on the same terms. These clauses are important when investors are involved.

Board composition and reserved matters

You can agree how many directors there will be, who appoints them, and which decisions need shareholder approval. Reserved matters are a list of major decisions, such as borrowing over a set amount, issuing new shares, or changing the business, that cannot happen without a specified majority of shareholders agreeing.

Dividend policy

Set out when profits can be paid out as dividends and how any dividend is shared. This avoids arguments about whether to reinvest or distribute cash.

Deadlock resolution

If two 50/50 shareholders disagree on a key issue, the company can grind to a halt. A deadlock clause sets out a process for resolving this, such as mediation, a buyout mechanism, or a casting vote. Decide on this before you need it.

Restrictive covenants and confidentiality

Shareholders often have access to sensitive business information. The agreement can prevent them from sharing it or from setting up a competing business while they are a shareholder and for a limited period after they leave. Any restriction must be reasonable to be enforceable, so get legal input on drafting.

Dispute resolution

Agree in advance how disputes will be handled. Starting with negotiation or mediation is usually cheaper and faster than going to court.

Practical tips for early-stage startups

• Keep it proportionate. A two page agreement between two co-founders can be enough. Do not over-engineer before you have investors.
• Make sure the agreement and your articles of association do not conflict. If they do, it creates confusion about which rule applies.
• Review the agreement whenever your shareholding changes, such as after a funding round or a founder departure.
• Avoid copying a US template. Shareholder rights in the UK are governed by the Companies Act 2006, and US documents often use different legal concepts.

Getting help

A shareholder agreement is a legal document, and getting the wording right matters, especially around drag-along, tag-along, and restrictive covenants. For anything beyond the simplest two founder situation, it is worth asking a solicitor to draft or review the agreement. This guide is general information, not legal advice, and you should always get advice specific to your company's circumstances.