England – Who owns software IP I built as a side project

Hi all,

Looking for some guidance on intellectual property and employment in England.

I work in a non‑technical, admin‑type role. My contract and job description are about admin/support, not software development, coding or IT. I’m not in an IT, web, or development team.

Separately, I run/was planning a small side business and developed a software tool/platform to automate certain admin processes that are common in my sector. I started and mainly built this as a personal business project in my own time, on my own equipment, with the intention of selling it more widely (not just to my employer). The tool is generic enough that it could be used by many organisations.

Later, I realised the same tool (or part of it) could help with some of the repetitive admin in my job. I:

• Was never asked or instructed by my employer to build this tool.

• Was not required by my job description to design or develop software.

• Did most of the core development in my own time, outside work, for my own business.

• May have done some tweaks/configuration that relate to my employer’s processes.

There is an internal IP policy which says that “Staff IP” created “in the course of employment” is owned by the employer, but my role is officially admin and I was never commissioned or requested to create any software.

My questions:

1. Under UK law and typical IP policies, how much risk is there that the employer could claim ownership of the entire software product, given:

• It was conceived and developed as a side‑business product,

• My role is admin and not development,

• They never requested or commissioned it,

• But I did later use/adapt it in my job?

2. Is there a common approach where:

• I retain ownership of the core platform as my own business IP, and

• The employer only has rights to any customisations/config created for them or to continue using the version they already have?

3. Would it be reasonable/normal to treat the employer as a potential licensee or customer of my tool (i.e. a licensing agreement from my business to them), instead of them owning it outright?

TLDR: Admin employee in England built a generic software tool as a side‑business project, mostly in their own time, Employer has an IP policy claiming anything created “in the course of employment”, but the tool wasn’t requested, isn’t part of the job description, and is meant for wider commercial use. OP wants to know if the employer can claim ownership of the entire product or just employer‑specific customisations, and whether treating the employer as a paying licensee/customer is a better route than them owning it outright.