Fractional CFO vs Outsourced Finance Function
One keeps your books right. The other decides what to do about what they say. Most UK startups need both, and buying the wrong one first is an expensive way to find out.
Quick answer
An outsourced finance function is a processing capability. It closes your month, files your VAT, runs payroll and hands you management accounts. Buy it as soon as the admin outgrows a spreadsheet.
A fractional CFO is a decision capability. They build the model, price the product, plan the runway and answer to your board. Buy it when the decisions get expensive, which for most startups is the raise before Series A.
What each one actually delivers
Outsourced finance function
Bookkeeping firms, finance-as-a-service providers, outsourced FD packages
- Bookkeeping and transaction processing
- Payroll and pension administration
- VAT returns and statutory filings
- Monthly management accounts to a standard template
- Accounts payable and receivable runs
- Year-end pack prepared for your accountant
Fractional CFO
Senior finance judgement, retained for part of a week
- A financial model that answers questions the accounts cannot
- Pricing and unit economics analysis with a decision attached
- Scenario planning and rolling forecasts against your runway
- A data room and the diligence answers behind it
- Board packs written for the people who read them
- Ownership of the number when an investor pushes back
Side-by-side comparison
| Factor | Outsourced finance | Fractional CFO |
|---|---|---|
| Primary output | Accurate historical records | Forward-looking decisions |
| Time horizon | Last month | Next 18 months |
| Typical engagement | Fixed monthly fee per volume | Retainer scoped to your stage |
| Who it reports to | Your finance lead or founder | Founder and board |
| In a fundraise | Supplies the underlying numbers | Builds and defends the case |
| Accountable for | Accuracy and deadlines | Financial judgement and outcomes |
| Replaces the other | No | No |
For most startups the answer is both
These two roles are complements. The outsourced provider produces clean, timely, reconciled numbers. The fractional CFO takes those numbers and decides what they mean for pricing, hiring, runway and the next raise. Paying a CFO rate for bookkeeping wastes money; asking a bookkeeping provider to own a fundraise asks for judgement you did not buy.
The sequence that usually works
Bookkeeping first, from the moment invoices and payroll stop fitting in a spreadsheet. Fractional CFO second, six to nine months before you intend to raise, so the model and the data room are built before an investor asks for them.
The mistake we see most
Founders assume that a provider producing management accounts is also watching the runway. Management accounts describe what already happened. Nobody is forecasting unless you have asked someone to, and named them.
How they should work together
A fractional CFO should reduce your outsourced bill over time by tightening the chart of accounts, cutting rework at month-end and settling what gets reported. If the two are duplicating each other after a quarter, the scope was drawn wrong.
Comparing the individual roles instead of the providers? Read Fractional CFO vs Accountant vs Financial Controller. Weighing a permanent hire? Read Fractional CFO vs Full-Time CFO.
Financial Leadership
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