Financial Controller (Lead) | Series A Climate Tech Start-Up | Remote

The Client

Harmonic is delighted to be partnering exclusively with a highly mission-driven Series A Climate Tech start-up. The business is internationally active and well-funded. Despite its purpose-led mission, the organisation operates with the pace, rigour, and ambition of a tech scale-up, with a senior leadership team drawn from commercial, financial, and technical backgrounds. As the organisation enters a critical next phase of maturity, finance is being brought fully in-house for the first time. This creates a rare opportunity to take ownership of a finance function in transition, shaping systems, controls, and commercial insight from the ground up. This role will play a central part in ensuring financial resilience, operational discipline, and smarter use of capital during a period of organisational change and growth.

The Role

Reporting into the COO, this Financial Controller (Lead) position is broad, hands-on, and highly impactful. You will take ownership of day-to-day financial control while also acting as the senior finance lead on systems, compliance, and more complex analytical work. The remit spans core financial operations, statutory reporting, with longer term exposure to treasury and cash management, and supporting commercial decision-making across the organisation. This is not a purely “steady-state” FC role. The business is undergoing significant finance transformation, including internalising processes from external providers, migrating finance systems, and standing up a scalable UK-based finance operation to support international activity. The role is offered on a 12-month fixed-term basis, with a clear expectation that it will become permanent. This is an ideal opportunity for an experienced Financial Controller who enjoys rolling up their sleeves, building structure where there is opportunity, and partnering closely with senior stakeholders in a fast-moving, purpose-driven environment.

Key Responsibilities

• Bring all FinOps and Financial Reporting processes in-house
• Own the month-end and year-end close, ensuring timely, accurate management accounts and balance sheet integrity.
• Oversee transactional finance including AP, AR, payroll, bank reconciliations, and payment runs.
• Maintain and strengthen internal controls as finance is brought in-house.
• Lead statutory reporting and audit processes across relevant jurisdictions, working with external auditors and advisors.
• Support the preparation of formal reporting packs and financial sections of organisational reporting.
• Own cash flow forecasting, monitoring, and reporting.
• Improve treasury management, including FX exposure, banking arrangements, and interest optimisation.
• Identify opportunities to improve capital efficiency, reduce costs, and strengthen financial sustainability.
• Support budgeting, forecasting, and more complex financial analysis alongside senior stakeholders.
• Lead the migration and optimisation of finance systems, ensuring they are scalable and fit for purpose.
• Bring finance processes in-house from external providers, embedding best practice and documentation.
• Support finance process improvements across the wider organisation, including training non-finance teams where needed.

Qualifications

• Fully qualified accountant (ACA / ACCA / CIMA or equivalent).
• Proven experience in a Financial Controller or senior finance role within a scaling, fast-paced environment.
• Strong grounding in financial control, statutory reporting, audit, and compliance.
• Experience owning or improving finance systems and processes.
• Excellent Excel and financial modelling skills, comfortable working with complex data.
• A pragmatic, solutions-focused mindset, able to balance accuracy with pace in a changing environment.
• Confident communicator, comfortable partnering with senior stakeholders outside of finance.
• Experience in SaaS, tech, or venture-backed scale-ups.
• Exposure to international or multi-entity structures.
• Experience internalising finance from outsourced providers.
• Hands-on treasury, cash management, or FX exposure.

Start Date: ASAP

Contract: 12-month Fixed-Term (strong likelihood of conversion)

Location: Remote-first, UK-based

If you’re looking for a high-impact Financial Controller role where you can genuinely shape a finance function within an ambitious climate tech organisation, please send your CV directly to . 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.