Senior .Net Developer (Billing Systems Essential)

About the role

We are recruiting a Senior .Net Developer to join a global trade business on a 2‑year fixed‑term contract. The position is hybrid, requiring at least three days per week in the Southampton office, and focuses on modernising a complex legacy billing platform.

Key responsibilities

• Analyse and stabilise an existing, heavily customised billing system.
• Reverse‑engineer undocumented code and produce clear technical documentation.
• Collaborate with Billing SMEs, Business Analysts and programme stakeholders to bridge technical implementation and real‑world billing processes.
• Support ongoing enhancements while aligning with a multi‑year billing transformation programme.
• Utilise AI‑assisted tooling to improve code understanding, documentation and delivery.

Required profile

• Strong .Net development experience on complex, business‑critical billing or financial transaction systems.
• Proven ability to take ownership of legacy codebases, troubleshoot and refactor.
• Experience delivering solutions that vary per client requirements.
• Comfortable working in a fast‑paced transformation environment.

Required skills

• .NET
• C#
• Billing systems
• Financial systems

What we offer

• £60,000‑£65,000 per year plus a 10% performance bonus.
• 8% pension contribution and private medical cover.
• Hybrid working model (minimum 3 days onsite).
• Opportunity to work on a high‑impact AI‑enabled modernisation programme.