Senior .Net Developer (Billing or Financial Systems Essential)

About the role

We are seeking a Senior .Net Developer to join a globally connected business in Southampton on a 2‑year fixed‑term contract. The role focuses on a complex, heavily customised billing platform and will involve both stabilisation and transformation work in a hybrid setting (minimum three days onsite).

Key responsibilities

• Analyse and reverse‑engineer legacy billing code to uncover undocumented behaviours.
• Produce clear technical and business documentation for existing functionalities.
• Collaborate with Billing SMEs, Business Analysts and programme stakeholders to bridge technical implementation with real‑world billing processes.
• Support ongoing enhancements and ensure alignment with the long‑term migration to a new enterprise billing system.
• Apply AI‑assisted tooling to improve code understanding, documentation and delivery efficiency.

Required profile

• Strong .Net development background with experience on complex, business‑critical systems.
• Proven experience in billing, invoicing or transactional financial products that are tailored to different customer needs.
• Ability to take ownership of existing systems, read and understand legacy code, and communicate findings to both technical and non‑technical teams.
• Comfortable working in a fast‑paced transformation programme and collaborating across multiple disciplines.

Required skills

• .NET
• Billing systems experience
• Financial product experience
• AI‑assisted tooling

What we offer

• £60‑65k salary plus 10% bonus
• 8% pension contribution
• Private medical cover
• Hybrid work model (minimum 3 days in Southampton office)
• 2‑year fixed‑term contract with potential for extension
• No visa sponsorship available