How to decide equity split between co-founders in a UK startup

Deciding how to split equity between co-founders requires balancing contributions, future commitments and risk while protecting the business. There is no single correct percentage; the right split depends on what each founder brings and agrees is fair at the outset.

This guide outlines practical steps for UK early-stage founders and e-commerce sellers, including how to use legal templates, set up vesting schedules and avoid common mistakes that can cause problems later.

Why equity split matters in the early days

Equity represents ownership and influences control, profit shares and what happens if a founder leaves. For bootstrapped e-commerce startups, an unbalanced split can create resentment when one founder works full-time while another contributes less. Getting the split right early reduces disputes and makes future funding discussions simpler.

Begin by listing all contributions: cash invested, intellectual property, customer lists, technical skills, industry contacts and time already committed. In e-commerce, one founder might bring supplier relationships while another provides the website development expertise. Document everything in writing before discussing percentages.

Practical steps to agree an equity split

Follow these steps in order:

Hold an open conversation about expected future contributions, not just past ones. Agree on roles, time commitments and decision-making responsibilities.
Assign approximate values to each element. A founder working full-time for six months without salary might reasonably expect more equity than one contributing part-time.
Start with an even split as a baseline and adjust based on the discussion. Many UK founder teams begin near 50/50 and move to 60/40 or 70/30 where contributions differ significantly.
Write down the agreed split and the reasoning. This record helps if memories fade or new information emerges.
Review the split again after three to six months once the business has traction.

Use a simple spreadsheet to model different scenarios and their effect on ownership over time.

Using legal templates and agreements

Once you agree the split, formalise it. Founders' agreements and shareholders' agreements set out equity, voting rights, what happens if someone leaves and how disputes are resolved. Free or low-cost templates are available from Companies House resources and reputable legal platforms, but always adapt them to your situation.

Key sections to include are equity allocation, vesting terms, intellectual property assignment, non-compete clauses and exit provisions. For e-commerce businesses, ensure the agreement covers ownership of the website, supplier contracts, customer data and brand assets. Check current requirements on GOV.UK and Companies House before filing any documents. Professional legal review is advisable even when starting with a template.

Vesting schedules and why they protect everyone

Vesting means founders earn their equity over time rather than receiving it all on day one. A typical schedule might spread ownership over three or four years with a one-year cliff. This protects the business if a founder departs early.

Example: With a four-year vesting schedule and one-year cliff, a founder with 50% equity would receive nothing in the first year. After 12 months they vest 12.5%, then approximately 1% per month until fully vested at four years. If they leave after six months they keep nothing; if they leave after two years they keep 25% and the remainder returns to the company.

Include provisions for accelerated vesting in the event of acquisition. Document the schedule in the shareholders' agreement. This approach is standard with UK investors and helps first-time e-commerce founders avoid losing significant ownership to someone who stops contributing early.

Common pitfalls for first-time e-commerce founders

Many first-time founders make these mistakes:

-splitting equity equally without considering different time commitments or opportunity costs.
Failing to agree what happens if one founder wants to leave or work on another venture.
Ignoring the need for vesting, which can leave the business vulnerable.
Over-valuing an idea compared with execution. In e-commerce, building reliable supply chains and achieving consistent sales usually matters more than the original concept.
Not documenting contributions or decisions, leading to disagreements when revenue starts coming in.
Assuming verbal agreements will be remembered the same way by everyone.

Another frequent error is delaying the founders' agreement until after the first sales or grant application. Complete the agreement before opening a business bank account or signing supplier contracts.

Handling future changes and investment readiness

Build flexibility into your agreement. Include a clause for adjusting equity based on clearly defined future contributions, such as securing a large contract or working additional unpaid hours. Set a process for any changes, requiring unanimous or majority agreement in writing.

When seeking loans, grants or angel investment, investors will examine your cap table and founders' agreement. Clean equity splits with vesting and proper documentation make the business more investable. Keep records of all share allotments and file them promptly at Companies House. Regularly review ownership as the team grows or roles change.

Final checks before committing

Before signing any documents, each founder should consider these questions independently:

Does this split reflect both past and expected future input?
Am I comfortable with the voting rights and control this gives?
Do I understand the vesting implications if I or my co-founder leaves?
Have we agreed how to handle underperformance or disputes?

Discuss the answers together. It is better to resolve discomfort now than after the business gains momentum. Remember that tax rules, filing fees and legal requirements change; always check the latest information on GOV.UK, HMRC and Companies House or consult an adviser for your specific circumstances.

Organisations such as Loomworks in West Yorkshire can provide practical mentoring to help early-stage founders work through these decisions.

Frequently asked questions

Should we always split equity 50/50 between two co-founders?

Not necessarily. A 50/50 split can work when contributions and commitments are identical. In most UK e-commerce startups, one founder usually contributes more time, money, expertise or contacts. Adjust the split to reflect this and use vesting to protect the business. Document your reasoning clearly.

What is a vesting schedule and do we need one?

A vesting schedule releases equity to founders gradually over years, typically with a one-year cliff. It protects the company if a founder leaves early. Most professional investors expect vesting. Include it in your shareholders' agreement to avoid one founder keeping a large share without continued contribution.

Can we change the equity split after the company is formed?

Yes, but it requires agreement from all shareholders and proper documentation. New share allotments or transfers may have tax implications. Always update Companies House records. It is far easier to set a fair split at the beginning than to renegotiate later when emotions and valuations are higher.

Do we need a lawyer for a founders' agreement?

While templates are available, professional legal advice is strongly recommended. A lawyer can tailor the agreement to your e-commerce business, ensure intellectual property is correctly assigned and highlight issues you may miss. Costs vary; check current options on GOV.UK and legal service platforms.

What happens to equity if a co-founder leaves the startup?

This should be covered in your shareholders' agreement. With a vesting schedule, only the vested portion is usually kept. Unvested equity typically returns to the company. Clear buy-out terms, notice periods and non-compete clauses prevent disruption to the e-commerce operations.