Freelance Software Engineer Contract Template (UK 2026)

Freelancer ContractSoftware Engineer

Last updated: February 2025

When You Need This Contract

Freelance software engineer contracts share many requirements with web developer contracts but typically involve deeper system access, more complex IP considerations, and heightened security obligations. The contract must address code ownership across all repositories contributed to, security clearance and background check requirements, IR35 status determination, and the engineer's obligations around code quality standards, testing, and documentation. For senior engineers, the contract should also address architecture decisions and technical debt.

Key Clauses

  • Comprehensive IP assignment for all code, documentation, and technical designs
  • Code quality standards, testing requirements, and documentation obligations
  • Security requirements including background checks and access protocols
  • IR35 status determination and compliance provisions
  • Architecture and technical decision documentation

What to Watch Out For

  • Not conducting an IR35 status determination before engaging the software engineer, risking significant HMRC penalties
  • Failing to require adequate code documentation, making it impossible for other developers to maintain the code after the engagement ends

Sample Clauses

  • Sample IR35 clause: 'Both parties have assessed this engagement and determined that it falls [outside/inside] IR35. The key factors supporting this determination are: [right of substitution, control, equipment provision]. Both parties agree to review this determination if the working arrangements change materially.'
  • Sample code quality clause: 'All code shall be written in accordance with the project coding standards document, include unit tests with minimum [80]% code coverage, be accompanied by inline comments and API documentation, and pass the project's CI/CD pipeline before being considered complete.'

FAQ

How does IR35 affect a freelance software engineer engagement?

IR35 determines whether the engagement is treated as employment for tax purposes. Since April 2021, medium and large private sector businesses are responsible for determining the IR35 status of contractors they engage. Factors considered include the right of substitution, the degree of control over how work is done, and whether the contractor is part and parcel of the organisation. Incorrect determination can result in significant tax liabilities for the engaging business.

What code quality requirements should a freelance software engineer contract include?

Specify coding standards to follow, minimum test coverage percentages, documentation requirements including README files and API documentation, code review participation expectations, and the CI/CD pipeline the code must pass. Include a definition of done that all deliverables must meet before being accepted and paid for. This protects the client from receiving unmaintainable code.

Related Templates

Freelance Web Developer Contract Template (UK 2026)

Freelancer Contract Template for SaaS Businesses (UK 2026)

Generate this contract in 60 seconds

AccountsOS generates customised, UK-compliant freelancer contracts. From £10/month.

Get Started Free

This is guidance for UK businesses, not legal advice. Templates are illustrative. Consult a solicitor for complex matters.

View all templates