Senior Back-end Engineer (Legacy Maintenance & Tax)

Experience and Skills

• 5+ years of experience in backend development using .NET and C#.
  C1 English level or higher.
  Solid experience with legacy .NET Framework, Dapper, and Entity Framework.
  Proven experience working with legacy codebases, including reading and maintaining non-C# scripting languages such as PHP or Visual Basic syntax.
  Pragmatic testing experience with unit and integration testing focused on critical system paths.
  Full availability for synchronous collaboration during peak season (October to April, with critical focus in December and January).
  Hands-on experience with SQL.

  Skills
  C#
  Dapper
  Entity Framework
  SQL
  Backend Development

Projects

This senior role focuses on maintaining, debugging, and updating a critical legacy backend system within the US tax compliance and fintech space. Operating within a dedicated engineering team, the primary objective is ensuring system stability and implementing annual tax logic updates before strict regulatory deadlines. This position requires a pragmatic approach to software maintenance, prioritizing operational continuity over refactoring. You will take ownership of specific US state jurisdictions, translating complex tax regulations into precise technical logic. The environment involves working with a large, established codebase that includes .NET Framework and legacy scripting languages. Success in this role requires high autonomy, a strong tolerance for imperfect legacy code, and synchronous availability during peak seasonal periods.

Key Responsibilities

• Debug, maintain, and support C# and .NET Framework services in production to ensure absolute stability.
• Translate complex US tax compliance rules into precise, reliable technical logic.
• Maintain and update assigned US state jurisdictions, ensuring calculations and thresholds are updated annually before statutory deadlines.
• Analyze and maintain legacy scripting codebases without performing unauthorized refactoring.
• Collaborate with the engineering team via Jira, participate in peer code reviews, and resolve escalated production incidents.

Benefits

Work on business-critical US tax software with a large live user base and direct access to engineering leadership. This is a fully remote, full-time contractor role for candidates based in the listed LATAM locations, paid monthly in USD.

You will own critical annual tax updates and collaborate closely with a pragmatic engineering team, with potential for long-term collaboration.

Nice to Have

• PHP
• Visual Basic
• .NET Core