---
title: "How much equity to give to a late-joining co-founder?"
id: "435426"
type: "post"
slug: "how-much-equity-to-give-to-a-late-joining-co-founder"
published_at: "2026-10-11T22:52:11+00:00"
modified_at: "2026-10-11T22:52:11+00:00"
url: "https://seedlegals.com/resources/how-much-equity-to-give-to-a-late-joining-co-founder/"
markdown_url: "https://seedlegals.com/resources/how-much-equity-to-give-to-a-late-joining-co-founder.md"
excerpt: "You had an idea. You’ve been working on for a few months. You really need a co-founder. You meet somebody. Now the big question: how much equity to give them? You might be thinking it’s all your idea, so you’ll..."
taxonomy_category:
  - "Startup Guides"
  - "Video Zone"
---

1 min read

# How much equity to give to a late-joining co-founder?

Published: Oct 11, 2026

[Anthony Rose](https://seedlegals.com/resources/author/anthony/)

You had an idea. You’ve been working on for a few months. You really need a co-founder. You meet somebody.

Now the big question: how much equity to give them?

You might be thinking it’s all your idea, so you’ll give them 10% equity.

They might be thinking, no, they want 50% equity. You’re equal partners now.

Deciding how much equity to give a late-joining co-founder is one of the hardest problems. The big mistake that founders make is they **overestimate** the value of their idea and the time that’s been put in so far and **underestimate** the amount of work and value that both (or all three or four) founders will need to put into the company between now and an exit in maybe 5 or 7 years.

So I propose what I call the **Back to the Future** method – i.e. pretend that it’s 5 years from now. The company is now 150 people. You’ve each put in insane amounts of work, 7 days a week, to build and grow the company.

Or have you both put in the same amount of work? Maybe your co-founder still had a side job for the first year.

And how much **value** have you put in? Because it’s ultimately your relative value that’s more important than the time spent.

To help, I made a video on it:

Once you’ve figured out *how much equity* to give them, then the next step is to decide *the form of that equity*. Do you give them…

- Shares?
- EMI share options?
- Growth Shares?

To learn the most tax-efficient and best way to give equity to a late-joining co-founder, [see this SeedLegals article and video](https://seedlegals.com/resources/how-to-give-equity-to-team-members-and-advisors/)

## Related posts

[1 min read Notice and non-compete periods - what's standard for UK startups? There’s a lot of debate right now about a proposed government ban on non-compete periods. A group of well-funded ... Anthony Rose](https://seedlegals.com/resources/notice-and-non-compete-periods-whats-standard-for-uk-startups/)

[5 min read Why you can't validate your startup idea, and what to do instead Most founders think they have validated their startup idea. Here is why the evidence usually fails, and the three questi... Charles Hope](https://seedlegals.com/resources/validate-your-startup-idea/)

[4 min read Most founders don't think about GDPR until someone asks for their data Of course you ignore GDPR. Right up until you get an email “Send me all my data. Delete everything you have on me.” Sud... Laura Brentnall](https://seedlegals.com/resources/most-founders-dont-think-about-gdpr-until-someone-asks-for-their-data/)