Senior Staff Engineer - Tax Platform Engineering

About Gusto At Gusto, we're on a mission to grow the small business economy. We handle the hard stuff — payroll, health insurance, 401(k)s, and HR — so owners can focus on their craft and their customers. With teams in Denver, San Francisco, and New York, we support more than 500,000 small businesses nationwide and are building a workplace that reflects the people we serve. All full-time employees receive competitive base pay, benefits, and equity (RSUs) — because everyone who helps build Gusto should share in its success. Offer amounts are determined by role, level, and location. Learn more about our Total Rewards philosophy. AI is a fundamental part of how work gets done at Gusto. We expect all team members to actively engage with AI tools relevant to their role and grow their fluency as the technology evolves. AI experience requirements vary by role and will be assessed during the interview process. About the Role: We’re hiring seasoned engineers to join our teams that work on core platform capabilities, improving our existing systems for extensibility and scalability, and building the future of Gusto's Tax platform. As a Gusto Software Engineer at this level, you’ll be guiding projects end-to-end by influencing initial feature specs, understanding how to take existing systems closer to desired end states, executing on projects, and maintaining code that powers core experiences. If you’re interested in building elegant software with far-reaching effects in our modern economy, join us! About the Team: Payroll is the beating heart of Gusto’s business. The Tax team ensures Gusto customers remain compliant and confident by managing every aspect of payroll taxes—including setup, calculation, payments, filings, and year-end communications. We design seamless, end-to-end experiences that simplify complex processes and build the infrastructure that keeps taxes accurate and on time. By combining reliable systems with thoughtful design, our team makes one of the most complicated parts of running a business simple for employers. Tax is a stabilizing pace layer at Gusto: continuity and trust are paramount, change is deliberate, and impact is wide. The domain is highly complex and offers the opportunity to engage in system design that simplifies this for customers. Here’s what you’ll do day-to-day: • Design, build, and test the platform that supports tax compliance for millions of people • Help scale one of the largest Ruby/Rails and TypeScript/React applications in the world • Collaborate on complex and ambiguous problems with partnerships from Engineering, Product Management, Design, Data Science, Compliance, Operations, and other cross-functional teams • Improve the productivity and happiness of our teams with the services, tools, and APIs you build. • Build guardrails into the Tax platform that enable Gusto to safely leverage agentic AI to interact with tax concepts in a way that ensures compliance, accuracy, stability, and reliability. • Engage in a highly supportive environment working with others to drive productivity and innovation • Own and drive the technical strategy and roadmap for your team’s domain area in alignment with team and group-level OKRs • Identify and prioritize long-term investments to improve foundational systems and architecture • Lead improvements to incident response processes, tooling, and culture to enhance system reliability and team effectiveness • Mentor and develop engineers on your team working to create holistic and scalable solutions. Track record of elevating team capabilities through pairing, code review, and knowledge sharing. Here’s what we're looking for: • Successful applicants have at least 10+ years of experience • Experience in designing and developing robust, distributed systems using multiple general-purpose programming languages • Experience influencing and guiding the work of multiple teams on scaling, refactoring, and optimizing legacy products • Experience architecting, building, and testing large-scale production level code • An aptitude and interest in bringing clarity and simplicity to complex and ambiguous problems • Ability to communicate technical complexity and help facilitate informed tradeoffs • Enthusiasm for a highly collaborative, test-driven environment • Able to build maintainable, structured, well-documented code • Experience building fault-tolerant, mission-critical software • Experience building products in highly regulated and high risk domains • Experience in one of these domains is preferred: Payroll, Taxes, or Compliance • Familiar with current AI tools (LLMs, Agents) and their shortcomings / benefits • Embeds AI in daily development workflow (scaffolding tests, summarizing docs) to measurably reduce cycle time. • Mentors engineers on effective AI usage and helps develop an AI strategy for other engineers • Bonus: Experience with Ruby on Rails, Typescript, and React Our cash compensation for this role is targeted at $189,000–$236,000 per year in Denver and most remote locations, and $223,000–$278,000 per year in San Francisco and New York. Stock equity is offered in addition. Final offer amounts are determined by multiple factors, including candidate experience and expertise, and may vary from the ranges listed above. At Gusto, we don't use titles the traditional way, as a signal of rank or hierarchy. Instead, our titles describe two things at once — your craft (what you do, e.g. Engineering, Design) and your scope of ownership (what you're accountable for) — which is why you'll see something like "Head of X" instead of a rank word like "Director" that tells you neither. Because of this, the title on this posting may look different from what you'd expect based on the scope and seniority of the role, and from how similar roles are typically titled elsewhere. If you have questions about how this role compares to your current title or level, your recruiter can help translate. Gusto has p