Financial Controller in London

Role: Fixed term (1 year), full-time, maternity cover

About you

You take our mission personally. That means fully committing even when the picture is incomplete, delivering value incrementally and urgently, and holding yourself – and others – to a high standard. You don’t accept mediocre work, but you also don’t faff around: you’re biased towards action, and you know the difference between rigour and unnecessary process. You’re self-aware, actively giving and receiving feedback to drive continuous improvement. You prioritise high-impact actions, confident in your strengths but also aware of your growth areas. You make decisions despite uncertainty, always keeping the mission front and centre. You’re a subject matter expert but like to win as a team. That means collaborating effectively, pivoting quickly when the mission demands it, and staying laser-focused on what actually moves the needle. You thrive under pressure, lean into change, and bring optimism and curiosity to problems that don’t have obvious solutions.

In this role, you’ll bring a pragmatic, low-bureaucracy approach to financial management. You’ll implement efficient, scalable processes that enable sustainable growth without unnecessary complexity. With a sharp eye for detail and strong communication skills, you’ll translate financial insights into actionable recommendations for the leadership team.

About the role

We are looking for an experienced Financial Controller to provide maternity cover for a 12 month period. This is a hands‑on role responsible for maintaining the integrity and accuracy of TransitionZero’s financial operations during a critical growth phase. Because you will be our sole finance person you manage end-to-end, from the administrative to the strategic. You will oversee day-to-day finance activities, prepare budgets and management reporting, monitor project finances, and ensure compliance with charity and accounting regulations. Specific projects will include implementing new approval workflows, supporting our annual audit, and strengthening internal expense policies. You will report to our COO. This role requires strong technical accounting skills coupled with the communication skills to partner cross‑functionally in a fast‑paced environment. You will work closely with the executive team to deliver accurate, timely financial information that informs strategic decisions.

Responsibilities

• Maintain and update the financial model for management and forecasting purposes, proactively flag risks and opportunities.
• Oversee day‑to‑day bookkeeping including invoicing, bank reconciliation, payroll, and payment runs.
• Prepare annual budgets and provide quarterly updates on income and expenditure against targets.
• Manage the budget day‑to‑day and approve expenditure requests.
• Produce and review monthly management reporting.
• Monitor project budgets and provide analysis on restricted/unrestricted funding.
• Ensure all grant income and expenditure is accurately logged and reconciled.
• Proactively manage cash flow to prevent shortfalls, and oversee debtor management.
• Lead on developing budgets and financial reports for grant applications and reports.

Audit & Compliance (20%)

• Lead the annual audit process, liaise with external auditors and prepare schedules and documentation, and address audit findings.
• Implement robust financial controls, approval hierarchies, and compliance processes.
• Ensure compliance with charity and company accounting regulations and reporting requirements.
• Prepare statutory accounts in compliance with charity accounting standards and regulations for the Trustee Report.
• Manage monthly payroll and correspond with HMRC as necessary; ensure compliance with statutory pay rules (e.g. SMP) and benefits in kind.
• Manage VAT: prepare and submit quarterly VAT returns to HMRC, review VAT position, and ensure correct proportionate claiming.

Process Improvement (10%)

• Drive initiatives to reduce manual effort through automation and process improvement.
• Proactively identify opportunities to strengthen finance operations for scale.

Skills and experience

• Qualified accountant with 4+ years of experience.
• Experience in the charity or non‑profit sector.
• Proven ownership of the full finance function – comfortable being the sole finance person.
• Strong experience managing grants‑based funding – both restricted and unrestricted – including allocation, monitoring, and reporting: ideally £5m+ annual grant income.
• Experience preparing and leading an annual audit process.
• Solid understanding of VAT for charities, including quarterly returns and proportionate claiming.
• Proven track record of delivering accurate, timely financial reporting and forecasting.
• Highly skilled with accounting software, financial modelling, and data analysis.
• Proactive communicator skilled at surfacing issues and opportunities early.
• Strong relationship‑builder able to translate financial concepts to non‑finance audiences.
• Structured and detail‑oriented, but also flexible and solution‑focused.
• Comfortable working independently and managing projects end‑to‑end.
• Energised by the challenges of a fast‑growing, mission‑driven organisation.
• Experience implementing financial process automation and improvements.
• Experience with Xero specifically.

About us

TransitionZero is a climate tech non‑profit founded in 2021. TransitionZero builds software to reduce the time to build clean energy at scale. We pioneer open‑access and open‑source tools that make electricity system modelling more transparent, accessible, and actionable for governments, financiers and grid operators worldwide. Our flagship tool, Scenario Builder, enables policymakers, planners and investors to rapidly build, analyse and share energy system and electricity grid models without coding expertise or external consultants. Supported by model‑ready datasets, training and market insights, our tools strengthen in‑house capacity and support resilient, affordable and locally‑led energy transitions. At TransitionZero, we understand that diversity is an essential component of a successful team, whether that be diverse ways of thinking, personal or professional backgrounds, or skills. We aim to be the most talented non‑profit in our vertical through our culture of ownership and adaptability.

Enhanced competitive pension scheme – auto‑enrollment from day 1

25 days annual leave (excluding UK public holidays) and additional discretionary days off such as over the festive period

20 days of annual allowance to work from anywhere in the world

Hybrid working and core working hours model

Annual allowance to set up your home office

Annual budget and dedicated leave time for relevant training courses

Enhanced gender‑neutral parental leave (16 weeks fully paid)

Private healthcare following the successful completion of the probation period

Yearly team offsites

Our commitment to diversity, equity, and inclusion

Studies have shown that some people from marginalised or underrepresented groups are less likely to apply to a role unless they meet all of the hiring guidelines or qualifications. Whoever you are, even if you don't meet all of the criteria, if you can demonstrate a variety of skills and experience relevant to this role, we encourage you to apply as you might just be the candidate we hire! At TransitionZero, we’re looking for people who are genuinely passionate about what they do, and we welcome all people, regardless of their background. If you would like to discuss any reasonable adjustments to the application or hiring process that may better facilitate your participation, please contact our People Team for an informal chat. We will make every effort to respond to your request for assistance as soon as possible.