Principal Engineer CoCounsel Audit

Thomson Reuters•Frisco, TX

2d•$158,900 - $340,000•Hybrid

About The Position

This posting is for proactive recruitment purposes and may be used to fill current openings or future vacancies within our organization. Thomson Reuters is building the AI platform that will power the next decade of tax, accounting and audit products, including CoCounsel Audit, a suite of AI‑native products used by accountants on real client work every day. As a Principal Software Engineer, you will own core backend and AI orchestration systems that turn frontier models into reliable, production‑grade workflows at scale. This role is for the CoCounsel for Audit team, formed from the recent acquisition of the startup Materia. About the role: Own the AI backbone: You will be the principal engineer responsible for the backend and orchestration layer powering AI agents, conversations, workspaces, and knowledge base across CoCounsel for Audit. Shape the company's AI platform and patterns: Define patterns for building MCP servers, designing agents, novel uses of LLMs, experimentation, and scalable infrastructure. Your decisions will influence multiple product lines, not just a single feature. Work at real production scale: Build and evolve systems that operate over millions of documents, highly structured tax data, ever changing laws, and thousands of concurrent AI interactions from accountants doing time‑sensitive work. Small team, big surface area: Join a tight group of senior engineers and researchers shipping quickly, with direct access to product leadership and customers. Think ownership of a startup with the runway of a public company. Great fit for managers who miss building: This role is intentionally designed for senior engineers and engineering managers who want to move back into a high‑impact IC track. You keep the scope and influence of an EM – driving multi‑team initiatives, setting technical direction, mentoring senior engineers – but spend most of your time in the code and architecture of AI systems instead of in 1:1s and status meetings.

Requirements

Bachelors Degree in Computer Science, Computer Engineering, Related Field, or Equivalent Experience
8-10+ years of experience in backend development, building scalable web services and APIs.
Deep Python expertise and experience with production systems using frameworks like FastAPI (or similar), relational databases (PostgreSQL or equivalent), and a major cloud provider (AWS preferred).
Strong background in distributed systems: data modeling, API contracts, observability, resilience patterns, and performance tuning under load.
Proven track record owning large, complex projects end‑to‑end: architecture, execution, rollout, and long‑term operation.
Excellent communication skills and the ability to partner with product, design, and ML teams in a fast‑moving environment.
Demonstrated interest in AI systems and new engineering paradigms: LLMs, agents, retrieval, or similar – you care about what “AI‑native” software should look like.

Nice To Haves

Hands‑on experience integrating LLM APIs (e.g., OpenAI, Anthropic) into production applications, including prompt/response management, cost controls, and safety considerations.
Experience with AI‑adjacent infrastructure: vector databases, embeddings, semantic search, or custom retrieval pipelines.
Opinions and experience around automated testing, reliability, and release practices for systems with nondeterministic model behavior.
Prior experience in domains where correctness, auditability, and compliance matter (fintech, tax, audit, legal, or similar), or strong interest in applying AI in those contexts.
Many of our strongest candidates have bounced between EM and senior IC roles. If you’ve been managing for the last few years and want to get closer to the hard technical problems again – without giving up scope or career progression – this principal IC role is built for that pivot.

Responsibilities

Technical leadership and cross‑functional influence
Lead multi‑quarter initiatives that cut across AI, product, and infra (e.g., a new orchestration layer, a low-latency retrieval system, or a unified knowledge base).
Mentor staff and senior engineers, raising the bar on system design, code quality, and AI integration practices across the org.
Be the expert in new model capabilities, collaborating closely with AI/ML engineers, researchers, designers, and PMs to translate industry improvements into reliable, user‑facing workflows that accountants trust.
Help shape the team’s roadmap, technical strategy, and engineering culture – from experimentation practices to testing, rollout, and postmortems.
Help define and lead the platform integration strategy across new and existing Thomson Reuters audit systems to provide world class content and solutions for our customers.
Design and own AI‑first backend systems
Architect and implement backend services (Python, FastAPI, PostgreSQL, AWS, Vercel) that power generative AI agents, complex workflows (e.g., tax filing, advisory, audit), and document‑centric experiences.
Build and evolve AI orchestration: routing, tool calling, MCP servers, multi‑step workflows, safety and guardrails, and robust error handling around third‑party LLMs (OpenAI, Anthropic, and others).
Scale, reliability, and performance
Design for high‑throughput, low‑latency AI workloads: caching, queuing, rate‑limiting, model failover, and cost/performance tradeoffs.
Work with large‑scale data: millions of documents, retrieval and search, vector stores, and indexing strategies tailored to tax and accounting use cases.
Establish and refine SLOs, observability, and incident response for AI systems that must be correct, auditable, and trustworthy in professional workflows.

Benefits

Flexible vacation
Two company-wide Mental Health Days off
Access to the Headspace app
Retirement savings
Tuition reimbursement
Employee incentive programs
Resources for mental, physical, and financial wellbeing
Hybrid Work Model
Flex My Way
Work from anywhere for up to 8 weeks per year
Grow My Way programming
Skills-first approach
Market competitive health, dental, vision, disability, and life insurance programs
Competitive 401k plan with company match
Competitive vacation, sick and safe paid time off
Paid holidays
Parental leave
Sabbatical leave
Optional hospital, accident and sickness insurance paid 100% by the employee
Optional life and AD&D insurance paid 100% by the employee
Flexible Spending and Health Savings Accounts
Fitness reimbursement
Access to Employee Assistance Program
Group Legal Identity Theft Protection benefit paid 100% by employee
Access to 529 Plan
Commuter benefits
Adoption & Surrogacy Assistance
Access to Employee Stock Purchase Plan