Head of US Tax | Tech-Led Accountancy for Startups | London

The Client

Harmonic are delighted to be partnering with a technology-led accountancy business built for the start-up ecosystem. A substantial in-house tech and product team sits directly alongside the accountants, using AI and software to automate compliance so its specialists spend their time on technical judgement and strategic input. Founded by successful entrepreneurs who have previously built and exited technology companies, the business is at an early but well-capitalised stage with a rapidly expanding client base. The culture is direct and meritocratic, and progression is tied to performance rather than tenure.

The Role

A newly created role to bring US tax capability in-house. Reporting directly to the CEO and co-founder in a flat structure, you will become the internal technical authority on US corporate tax, owning federal filings end to end and building the processes and quality framework around them. This is a hands-on role. Despite the title, you will be completing filings personally, with Forms 5471 and 5472, alongside direct client contact on calls where advisory questions arise. The distinguishing feature is the technology: you will work with the engineering and product teams to automate the workflows you encounter, building the systems rather than inheriting them. Over time, and in line with growth in the US client base, there is scope to build a small specialist team beneath you.

Key Responsibilities

• Own US federal tax compliance and filings end to end, delivering the work personally rather than reviewing only.
• Prepare and file Forms 5471 and 5472 across a portfolio of Delaware TopCo clients with UK subsidiaries.
• Act as the internal technical point of reference on all US tax matters across the business.
• Build the processes, controls, and quality assurance framework that sit around US tax delivery.
• Identify where US tax workflows can be automated and work with engineering and product to scope, test, and roll out AI-driven solutions.
• Quality assure work produced by the existing network of external CPAs, bringing delivery in-house over time.
• Support clients directly on video calls and by phone where advisory questions arise.
• Manage a growing portfolio, expected to sit between 50 and 150 clients and to increase as the business scales.

Requirements

• US CPA or IRS Enrolled Agent (either qualification is acceptable).
• 10+ years' US corporate tax experience, including direct, hands-on experience filing US returns.
• Practice background, with Big 4 or Top 10 firms preferred; strong in-house experience will be considered where the exposure is substantial and full time.
• Genuinely comfortable with hands-on delivery rather than purely advisory work.
• Confident communicator, able to hold technical conversations directly with founders and senior finance stakeholders.
• Able to operate autonomously, with the judgement to handle complex situations as the only dedicated US tax specialist in the business initially.
• Direct experience with Delaware TopCo and UK subsidiary structures.
• Exposure to tech-enabled workflows, or genuine interest in how AI is changing the tax profession.
• Experience building or improving compliance processes from a standing start.

Package

• Salary reviews every six months.
• Location: Central London (office based, 5 days per week) or fully remote within the UK.
• Start Date: ASAP, three month notice periods accepted.
• Visa sponsorship: Available where required.

At Harmonic, we are dedicated to fostering an inclusive and equitable workplace. We actively welcome applications from individuals of all backgrounds and assure you that every candidate will be thoughtfully considered for the roles we represent, without regard to race, religion, gender expression, disability, or sexual orientation.