The First 90 Days of Post-Merger Integration

Closing an acquisition can feel like crossing a finish line.

Months of diligence, negotiation, and paperwork are finally done. But for the employees, customers, and vendors of both businesses, the work of becoming one company is only beginning.

Large companies often assign a dedicated integration team to this stage. In a growing business, integration usually falls to the owner and a few leaders who are also running day-to-day operations. That makes the first 90 days especially important. They shape what employees believe about the deal, whether customers stay, and whether leadership can trust the numbers in front of them.

Before day one: Set the scope of post-merger integration

Not everything should be merged. The right scope depends on why the business was acquired in the first place. A company bought for its customer relationships needs a different plan than one bought for its equipment, its location, or its team's expertise.

Before closing, it helps to write down the reason for the deal in a sentence or two. Then sort the acquired business into two groups: what must connect to the parent company for that reason to pay off, and what's working well enough to leave alone for now. Keeping that distinction clear protects the parts of the business that made it worth buying.

Days 1 to 30: Stabilize

Communicate with employees early and plainly. People want to know who they report to, whether their pay and benefits are changing, and who to ask when something is unclear.

Even partial answers are better than silence, which tends to fill with rumor. Naming a single point person for questions gives employees somewhere to go.

Coordinate what customers and vendors hear. Decide who will contact key accounts, what they'll say, and when. A customer who hears three slightly different versions of the change from three different people will start to wonder what else is uncertain.

Protect payroll. The first payroll after closing should run correctly and on time, for every employee. It's one of the clearest signals employees get about whether the transition is under control.

Employment obligations belong in this stage, too, and California's rules deserve particular attention. The state treats accrued vacation as earned wages, and employees who are discharged must be paid all wages, including accrued vacation, at the time of termination.

Depending on how a deal is structured, employees may be formally separated from the seller at closing, even if the buyer rehires them right away. That's why the acquired company's vacation and PTO policies should be reviewed to determine whether balances must be paid out or can transfer to the buyer.

If the integration plan includes layoffs, federal and state notice requirements may also apply. These questions are best settled before closing, with guidance from HR professionals and employment counsel.

Days 31 to 60: Connect the systems and the reporting

Get to one reliable view of the numbers. Two businesses rarely categorize revenue and expenses the same way. Until the accounting systems are combined, decide how the reports will be brought together, which numbers leadership will review each week, and who is responsible for reconciling them. A consistent monthly close matters more at this stage than a perfect system.

Take inventory before migrating anything. List the tools each company uses for accounting, payroll, scheduling, customer records, and communication. Then prioritize the systems where errors are most costly, such as payroll and billing. Moving every system at once tends to create more disruption than it saves. The same principle applies here as with any new tool: fix the process before you change the technology it runs on.

Review access and approvals. Confirm who can approve payments, who has access to bank accounts, and who holds administrator rights to shared systems. Acquisitions often reveal responsibilities that depend entirely on one person, and they're much easier to address now than after something goes wrong.

Days 61 to 90: Align how work gets done

Choose one way to do the same job. When both companies handle invoicing, onboarding, or scheduling differently, pick the approach that works best, document it, and involve people from both sides in the decision. Employees are more likely to adopt a process they helped shape.

Clarify roles and ownership. Overlapping positions and unclear reporting lines slow decisions down. Updated job descriptions and a simple organizational chart go a long way.

Pay attention to culture in small places. Cultural differences rarely show up in mission statements. They show up in how quickly emails get answered, who is expected to speak in meetings, and how much a manager needs to approve. A few informal check-ins with the acquired team, especially key employees, can surface friction before it turns into turnover.

Measure progress against the reason for the deal. At the 90-day mark, revisit the rationale you wrote down before closing. Note what's on track, what's taking longer than expected, and what the next quarter should focus on.

A few questions worth asking

• Could every employee from the acquired company tell you who to go to with a problem?

• Is leadership reviewing one set of financial numbers, or two that don't quite match?

• Which parts of the acquired business are working well enough to leave alone?

• Has anyone asked the acquired team what still feels unclear?

Integration rarely finishes in 90 days. But by the end of the first quarter, employees should know where they stand, the numbers should be trustworthy, and leadership should have a clear sense of what comes next.

If you're preparing to close a deal or already working through one, MCDA CCG's M&A services include post-merger integration, alongside the HR, finance, and operations work it touches.