Finance Team Structure at Each Funding Stage: Seed to Series C

The Finance Function That Scales With You

One of the more persistent misconceptions about startup finance is that you simply add people over time. In practice, the finance function does not just grow: it transforms. The skills, tools, and governance structures appropriate at seed are categorically different from those required at Series C, and the transition between stages is where most finance function failures occur.

The failure mode is almost always the same: a company raises a significant round, the finance function stays in its previous configuration for 9 to 12 months longer than it should, and then the board notices that the FP&A output is insufficient for investor reporting, the management accounts are three weeks late, and the audit is raising material issues. At that point, the rebuild is expensive and disruptive. Getting the timing right is worth far more than getting it perfect.

The benchmarks and costs in this article reflect UK market rates as of mid-2025 and are based on the actual finance functions of companies at each stage. They are not theoretical ideals; they are what well-run companies actually spend.

Seed Stage: Founder-Led Finance

At seed stage, the finance function should be light by design. You have limited revenue, a small team, and a need to preserve capital for product development and customer acquisition. The finance overhead should reflect that reality.

The appropriate configuration is: a founder handling financial decisions (aided by a good accountant), an outsourced bookkeeper processing transactions, and a cloud accounting platform (Xero or QuickBooks) as the system of record. That is it. No Finance Manager, no FP&A analyst, no in-house accountant.

The cost at seed stage should be £500 to £1,500 per month, covering bookkeeping, payroll processing (if applicable), and quarterly or annual accountancy. Software costs are minimal: Xero at approximately £50/month, with payroll software if you have employees.

What the founder needs to own personally at seed stage: the cash flow forecast (even if it is a simple 13-week spreadsheet), the burn rate, and the runway calculation. These are not tasks to delegate when your runway is 12 months and your next raise is uncertain.

What triggers the upgrade from seed to Series A configuration

• You have raised Series A (typically £2m to £8m in the UK market) and have investor reporting obligations
• You have 15 or more employees and payroll is becoming material
• You are generating meaningful revenue and need accruals accounting, not just cash accounting
• The founder is spending more than half a day per week on finance administration and it is blocking product work

Series A: The Finance Manager and Fractional CFO Model

At Series A, the finance function needs to step up materially, but it does not yet need a full-time CFO. The appropriate model is a Finance Manager (or Management Accountant) for day-to-day operations, combined with a fractional or part-time CFO for strategic and investor-facing work. This combination gives you the coverage you need at a cost that is appropriate for the stage.

The Finance Manager at Series A is typically a qualified or part-qualified accountant (ACA, ACCA, or CIMA) with two to five years of experience. They own the monthly management accounts, payroll, accounts payable and receivable, and the basic FP&A (often still in Excel). The fractional CFO owns the board pack, investor relations, financial model, and strategic finance questions.

The total cost at Series A is typically £80,000 to £150,000 per year, comprising: a Finance Manager at £45,000 to £70,000 (depending on experience and location), a fractional CFO at two to three days per month at £1,200 to £1,800 per day, and software costs that begin to increase as you add FP&A tools (Mosaic, Runway, or similar) and upgrade your accounting system configuration.

Series B: Building a Real Finance Function

Series B is where the finance function needs to grow significantly in both headcount and systems capability. You have likely raised £10m to £30m, have 40 to 80 employees, meaningful revenue, and institutional investors with rigorous reporting expectations. The fractional CFO model is no longer sufficient: you need a full-time finance leader.

The full-time finance leader at Series B is typically a VP Finance or Finance Director, rather than a formal CFO title. This distinction matters: a VP Finance or FD is operationally focused and capable of running the finance function end-to-end, including the audit, the board reporting, and the financial model. A CFO implies a seat at the senior leadership table with strategic responsibility for capital allocation, M&A, and investor relations. At Series B, you need the former; at Series C, you typically need both (or a CFO who can do both).

The Management Accountant owns the monthly close, statutory reporting, and audit preparation. The FP&A Analyst owns the financial model, the board pack data, and the investor reporting pack. The total finance function cost at Series B is typically £300,000 to £500,000 per year, comprising the three to four FTE plus software, audit, and advisory costs. Finance as a percentage of revenue should be falling toward 2 to 3% by late Series B as the revenue base grows.

Series C: The Full Finance Leadership Team

At Series C, the finance function is a genuine department with a leadership structure. You have raised £30m or more, likely have 100 to 300 employees, significant revenue, and investors who expect institutional-quality finance processes. The audit is now a material exercise. Tax and transfer pricing are likely live issues if you have international operations. Treasury is a function, not an afterthought.

The CFO at Series C is a strategic leader, not just a finance operator. They own the capital allocation strategy, the investor relationships, any M&A activity, and the path to profitability narrative. The Financial Controller owns the financial reporting function end-to-end. The Head of FP&A owns the financial model and all forward-looking analysis. The Treasury Analyst manages cash, foreign exchange exposures, and banking relationships.

Total finance function cost at Series C is typically £600,000 to £1,000,000 or more per year, including FTE costs, audit (which at this stage is typically £150,000 to £300,000 for a Big 4 or mid-tier firm), tax advisory, and systems. Finance as a percentage of revenue should have fallen to 1 to 2%.

The Most Common Hiring Mistakes

The two hiring mistakes that appear most frequently in our work with founders are worth addressing directly, because they are genuinely costly to reverse.

Mistake 1: Promoting the bookkeeper to Finance Manager. The bookkeeper who has been with you since seed is a known quantity, available, and understands the business. Promoting them to Finance Manager when you raise Series A is tempting. It is usually a mistake. Bookkeeping and financial management are different disciplines. A bookkeeper processes transactions accurately; a Finance Manager builds accruals-based management accounts, owns the FP&A function, and is the primary contact for the auditors. These are categorically different skills. The bookkeeper may develop into this role over time, but the Series A finance function cannot wait for that development.

Mistake 2: Hiring a Big 4-trained Finance Director who has never worked at a startup. The reverse error is equally common at Series B. A Big 4-trained FD or CFO brings technical rigour, audit experience, and process discipline, all of which are valuable. What they frequently lack is the ability to operate without support infrastructure, to build financial models from scratch rather than reviewing them, and to manage the ambiguity and resource constraints of a pre-profitability company. The ideal hire at Series B is someone who has been through a similar growth stage before, whether at a startup or a fast-growing SME, and can build as well as review.

Systems and Tools at Each Stage

The systems question is closely related to the headcount question: the right systems enable a smaller team to do more, and the wrong systems at the wrong stage either create unnecessary cost or leave dangerous gaps.

• Seed: Xero or QuickBooks (cloud accounting), Google Sheets or Excel (cash flow), Stripe (revenue reporting if applicable). Nothing else.
• Series A: Xero upgraded configuration (departments, tracking categories), a dedicated FP&A tool or a well-structured Excel model, an expense management platform (Pleo or Soldo), and a payroll system (Sage Payroll or similar).
• Series B: ERP consideration (NetSuite is the most common choice at this stage), dedicated FP&A tool (Mosaic, Runway, Pigment), a procurement approval workflow, and a treasury management system if cash balances are significant.
• Series C: Full ERP (NetSuite or similar), dedicated FP&A platform, an HR and finance system integration, potentially a consolidation tool if there are multiple entities, and a data warehouse for finance reporting (dbt, Looker, or similar).

Key Takeaways

• The finance function transforms at each stage, not merely grows. The skills, tools, and governance appropriate at seed are wrong for Series B.
• At seed, keep finance costs at £500 to £1,500 per month. A founder and an outsourced bookkeeper are sufficient.
• At Series A, the fractional CFO combined with a Finance Manager is the most cost-effective structure, typically £80,000 to £150,000 per year in total.
• The transition to a full-time finance leader should happen at or shortly after Series B; the fractional model does not scale past that point.
• Finance as a percentage of revenue should fall from 3 to 5% at Series A to 1 to 2% at Series C as the revenue base grows.
• The most common hiring mistakes are promoting the bookkeeper and hiring the Big 4 trained FD who has never operated without a support structure.
• Systems choices matter: Xero is appropriate at seed; ERP consideration is appropriate at Series B. Implementing NetSuite at Series A is premature and expensive.