Cost Accountant jobs in United Kingdom

As PortSwigger scales beyond $50M in revenue, managing planning cycles and cost structures with precision is as critical as growing the top line. We’re seeking a commercially aware, analytically minded FP&A Analyst who can bring structure, discipline, and insight to financial planning, reporting, and analysis. This role will take ownership of company-wide cost planning, partnering with teams across the business, and supporting strategic decision-making that drives efficient growth.

This is a foundational finance role with high visibility and broad remit — ideal for someone ambitious who wants to shape the future of a growing SaaS business.

Owning the Company-wide Plan

• Build and maintain the full cost side of the company’s financial model — from gross margin through to net profit.
• Consolidate revenue and cost into the overall company plan, ensuring alignment with strategic goals.
• Lead execution of annual budgets and monthly outlooks.
• Partner with business leaders to understand spending plans, hiring needs, and cost drivers.
• Translate strategy into clear financial plans.

Reporting, Analysis & Decision Support

• Track actuals vs. budget, surfacing risks, variances, and opportunities early.
• Produce clear, actionable cost reports and insights for business leaders.
• Own and refine cost efficiency metrics (e.g., cost per customer, cost per employee).
• Provide analysis to inform strategic trade-offs on operating leverage, margin improvement, and investment priorities.
• Deliver high-quality board and management reporting on performance and outlook.
• Build dashboards and models that democratize financial insights across the business.
• Act as a thought partner to senior leaders, proactively suggesting optimizations.

Systems & Data Integrity

• Partner with Financial Control to ensure data integrity across ERP, HRIS, and financial systems.
• Support a clean month-end close and maintain consistent reporting structures.
• Continuously improve finance processes to enable speed, accuracy, and scalability.

• Business leaders have high confidence in budgets and actuals, actively using them to guide decisions.
• Cost reporting and forecasts are timely, reliable, and trusted at board and executive level.
• Finance is seen as a collaborative, trusted business partner rather than a back-office function.
• Key financial variances and risks are identified early, with mitigation plans in place.
• Financial models are clean, scalable, transparent, and well-understood by stakeholders.

• 3–5 years of experience in FP&A, commercial finance, or business management — ideally in SaaS or tech scale-up environments.
• Strong academic background in finance, accounting, or a quantitative field, ideally supported by professional qualifications (ACA, ACCA, CIMA, CFA) or working toward one.
• Advanced financial modelling skills, with experience building and owning complex, multi-driver models.
• Comfortable working directly with data (SQL and data extraction skills a plus).
• Experience with FP&A tools and automation platforms.
• Skilled at simplifying financial concepts for non-finance stakeholders.
• Strong understanding of SaaS metrics (e.g., LTV/CAC, Magic Number) and cost structures (headcount planning, R&D, G&A, cloud infrastructure).
• Proactive, detail-oriented, and commercially minded — you spot issues early and focus on impact.
• Passionate about efficiency and growth, leveraging AI and automation to improve processes.

Bonus if you have:

• Prior experience in scale-up or high-growth SaaS businesses.
• Exposure to IPO-prep or rapid scaling environments.
• Hands-on experience with modern FP&A software (e.g., Mosaic, Pigment).

• Motivated by scaling businesses effectively and influencing strategy, not just reporting numbers.
• Excited by SaaS business models and building driver-based financial plans.
• Passionate about exploring AI and automation in finance, moving beyond spreadsheets.
• Curious about operations, product, and strategy, and eager to broaden your scope beyond “just finance.”
• Ambitious to grow into a commercial leader with wide business impact.

• Energetic, dependable, and collaborative — known as an “unblocker” who gets things done.
• Analytical yet commercially aware — able to deep-dive into detail without losing sight of business impact.
• Curious and adaptable, always seeking smarter, more efficient ways of working.
• Enjoy experimenting with new tools and approaches, particularly in AI and automation.
• Thrive in autonomy but also value brainstorming, feedback, and open collaboration.
• Communicate clearly and simply, empowering others to understand and act on financial insight.

Why join us?

• We foster an inclusive and high-performance culture with a focus on work-life balance.
• We believe in rewarding people generously and offer a competitive salary based on individual skills and contribution.
• We host regular team events and have fantastic summer and winter parties.
• You’ll be part of a humble, supportive, and fun team that values collaboration, humour, and a strong sense of belonging.
• We offer share options, 8% employer pension contribution, life assurance, income protection, private medical insurance, and 25 days holiday (plus public holidays).
• Our working hours are flexible, with core hours from 9am to 4pm
• We work best when we are together on site