Finance Transformation
The Finance Leader's Guide to Systems Integration
1 December 2025
Most finance leaders are comfortable with accounting systems. Fewer are comfortable with the question of how those systems connect to everything else the business runs on: the CRM, the inventory platform, the ecommerce stack, the payroll system, the bank feeds. That connection layer, or the absence of it, determines how much manual effort the finance function carries and how reliable its data is.
This is increasingly a finance leadership problem, not just an IT problem. The decisions about what connects to what, in what direction, with what controls, have direct consequences for the quality of financial reporting and the efficiency of the finance team. Finance leaders who leave those decisions to IT alone get systems that work technically and fail financially. Understanding why implementations fail makes the case for finance-led decision making.
What integration actually means in practice
Integration between systems means that data created in one system is available in another without manual re-entry. An order placed in the ecommerce platform creates a financial record in the accounting system. A purchase order raised in the procurement system matches against an invoice when it arrives. A payroll run produces a journal automatically rather than requiring manual input.
Each of these connections eliminates a manual step that introduces error risk and consumes time. This is the three-tier automation problem in practice: system, process, and behaviour all need to work together. The aggregate effect across a business with multiple operational systems is significant.
The absence of integration means manual processes at every connection point. Someone exporting from one system, formatting the data, and importing into another. Or, more commonly, someone maintaining a spreadsheet that bridges two systems that do not talk to each other. These spreadsheets become load-bearing infrastructure that nobody is comfortable changing and nobody fully understands. The question of ERP versus spreadsheets is often really a question about whether the integration layer exists.
The finance leader’s role in integration decisions
Integration projects tend to get framed as IT projects. The finance leader is consulted on requirements and then waits for delivery. This framing produces systems that technically connect but do not serve finance well.
The finance leader needs to be actively involved in three decisions. First, what data needs to flow between systems and in what direction. The accounting system needs certain fields from the CRM, in a certain format, at a certain frequency. Finance knows what those are. IT does not, unless finance tells them clearly.
Second, what controls need to exist around the integration. Automated data flows can create problems at scale just as efficiently as they solve them. If the ecommerce platform posts incorrect data to the accounting system, the error needs to be caught before it affects the accounts, not discovered at month-end. The control design is a finance question.
Third, what the reconciliation process looks like. How does finance confirm that what went in matches what came out? What happens when it does not? These processes need to be designed alongside the integration, not as an afterthought.
Build vs buy
For most integration requirements, there are off-the-shelf solutions: middleware platforms that connect common business systems without custom development. These are usually the right answer. They are faster to implement, easier to maintain, and supported by vendors who understand both systems.
Custom integration makes sense when the off-the-shelf solutions genuinely do not meet the requirement, or when the cost and complexity of adapting them exceeds the cost of building something specific. In practice, the bar for custom development should be high. Bespoke integration is expensive to build and expensive to maintain, and the team that built it is often not the team that maintains it.
I have built custom integrations when no alternative existed, and the experience reinforced a clear preference for standard solutions where they are available. The flexibility of a bespoke solution comes with a maintenance burden that should be honestly accounted for in the build decision.
The data quality problem
Integration amplifies whatever is in the source systems. Clean data in, clean data out. Dirty data in, dirty data out, at scale and at speed.
Before integrating systems, it is worth understanding the data quality in each one. Supplier records with missing fields. Customer records with duplicate entries. Product codes that are inconsistently formatted. These problems become integration problems the moment you try to connect systems, and they are easier to fix before integration than after.
Maebh Collins is a Chartered Accountant (FCA, ICAEW) and finance transformation specialist with Big 4 training and twenty years of operational experience including building bespoke systems integrations in commercial environments.
Maebh Collins is a Chartered Accountant (FCA, ICAEW), Big 4 trained, with twenty years of experience building and running international businesses. She specialises in finance transformation, ecommerce operations, and digital strategy.