Senior Full-Stack Developer – Enterprise US Tax & E-Filing SaaS Platform

We are looking for an experienced Full-Stack Developer to help build a large-scale, cloud-based U.S. tax and e-filing SaaS platform for both U.S. and non-U.S. companies. The platform will allow businesses to calculate federal and state taxes, manage multiple entities, generate tax returns, complete e-filing workflows, make tax payments, model tax-saving scenarios, and maintain detailed compliance and audit records. The MVP will initially focus on corporate and multi-state taxation, with support for federal taxes and at least two pilot states. The system must be designed for future expansion into additional states, tax years, tax forms, individuals, and small businesses. The developer will work closely with the project owner and a U.S. CPA/tax-law specialist to ensure the tax calculations and compliance requirements are properly implemented. The developer will also assist with technical troubleshooting during the IRS software testing and registration process. This is a long-term project, with the initial MVP followed by continued development, additional tax jurisdictions, features, integrations, and production improvements. Preferred stack: React, Next.js, TypeScript, Python/Node.js, PostgreSQL, AWS, APIs, Docker, CI/CD.