Closing an acquisition is the start of the work, not the end of it. The first 100 days set the tone for how quickly the combined business steadies its operations, brings teams together, and starts to deliver the strategic and financial benefits that justified the deal in the first place.

For finance leaders, this is one of the most demanding stretches of the whole transaction. They are expected to keep the business running, give management and lenders confidence in the numbers, support decisions that cannot wait, and lay the groundwork for growth, all at the same time. In our experience at Hillpine, the difference between a smooth integration and a difficult one usually comes down to whether finance had a clear plan in place before completion rather than scrambling to build one after it.

1. Validate the Opening Financial Position

Start by confirming that the opening balances actually reflect the business you have bought. Check working capital, debt, cash, outstanding liabilities and every material balance sheet account against what was assumed at completion. Go back to the issues raised during due diligence and make sure each one has been resolved or properly reflected in the accounts, rather than quietly carried forward. We often see the completion accounts and the due diligence file drift apart in the first few weeks, and closing that gap early is what gives management, investors and lenders confidence in the numbers they are being asked to rely on.

2. Align Financial Reporting

Bring the two businesses onto a common language as quickly as you can. Standardise accounting policies, reporting calendars, KPIs, management packs and the month-end close so that leadership is comparing like with like. Until reporting is consistent, every performance conversation gets bogged down in reconciling definitions instead of acting on what the numbers are telling you. A shared reporting framework is what lets leadership compare performance across the group and make decisions at the pace integration demands.

3. Focus on Cash Flow and Working Capital

Keep a close eye on receivables, payables, inventory, liquidity, covenant headroom and any short-term funding needs. Integration puts pressure on cash in ways that profit alone will not show, and a business can look healthy on an earnings basis while quietly running short of cash. In the first 100 days, cash discipline matters more than margin. We recommend running a rolling 13-week cash flow forecast from day one, reviewed weekly, so that surprises surface while there is still time to do something about them.

4. Strengthen Financial Controls

Review approval workflows, segregation of duties, delegated authorities and the wider control environment under the new ownership structure. Founder-led businesses in particular often run on informal controls and a small number of trusted people, which works well right up until ownership changes and the founder steps back. This is also where key-person risk becomes real. If critical knowledge or sign-off authority sits with one or two individuals, document it and put cover in place before a departure exposes the business. Strong governance reduces operational risk, supports compliance, and underpins the reporting that everyone else is relying on.

5. Confirm Deal Assumptions

Turn the assumptions in the investment case into measurable targets covering procurement savings, operational efficiencies, revenue opportunities and shared services. Track one-off integration costs separately from recurring performance, because once the two blur together no one can tell whether the synergies are real. That clear separation is what allows management, and any incoming investors, to see value creation as it actually happens rather than taking it on trust.

6. Refresh Budgets and Forecasts

Rebuild the forecast around the combined business rather than stitching together two sets of pre-deal assumptions. Update revenue projections, operating costs, hiring plans, capital expenditure and EBITDA expectations so the guidance reflects the group as it actually is now. A forecast built on legacy assumptions gives false comfort, and it is usually the first thing lenders and boards test. Realistic numbers, even where they are less flattering, are worth far more than optimistic ones that unravel at the first review.

7. Evaluate Systems and Data Quality

Assess the ERP systems, chart of accounts, master data, reporting automation and data governance across both businesses. Clean, consistent data is what makes fast, reliable reporting possible, and poor data quality is one of the most common reasons integration timelines slip. You do not have to fix everything at once. Sort out the data that feeds core reporting first, then work through the rest as part of the roadmap.

8. Build a Clear Integration Roadmap

Set out the finance initiatives that matter most, such as system integration, reporting improvements, process standardisation and team alignment, and then sequence them. A phased roadmap running across the first 12 to 24 months makes ownership, timelines and success measures explicit, and it protects day-to-day operations from being overwhelmed by change. Trying to do everything in the first quarter is one of the surest ways to lose momentum.

9. Communicate Across the Business

Finance should be the single source of truth throughout integration. Keep up regular, honest communication with operations, HR, commercial teams, executive leadership, lenders and investors, so that issues get raised early and priorities stay aligned. In our experience, the finance teams that over-communicate in the first 100 days are the ones that build trust fastest, and that trust is what carries an integration through the harder decisions later on.

The First 100 Days Shape Long-Term Success

Successful acquisitions are rarely won or lost on the deal itself. They are decided by disciplined execution once the deal has closed. A finance function that delivers accurate reporting, protects liquidity, strengthens governance, measures synergies, refreshes forecasts and turns data into decisions gives leadership the visibility it needs to realise the value the deal promised. Getting finance integration right from day one is one of the clearest early signals of whether an acquisition will deliver the returns that justified it.

At Hillpine, we work alongside acquirers and management teams to build and run the finance integration plan through the first 100 days and beyond. If you are preparing for completion, or you are already in the thick of integration and want a steady second pair of hands, we would be glad to talk.