Here is the uncomfortable part. Most capable buyers get integration wrong, and they do not find out until the numbers tell them, long after they could have fixed it. They underestimate the work, they lose attention once the next deal appears, and too many walk in certain that because they wrote the check, their way must be the better way.
It is not always. Sometimes the company you bought does the thing better than you do, and the fastest way to destroy what you paid for is to make it look like you. This checklist is built to stop that. It does not assume one size fits all. Before you change anything, you decide your approach: preserve and strengthen, selectively integrate, or substantially consolidate. Then you protect what generates value before you improve it.
Get the editable checklist (XLS)
The full checklist as a spreadsheet you can assign, track, and work through with your team. Pre-close through day 100, with an owner and status on every item, plus an opening baseline tab.
One email with the download, and occasional Building Results notes. Opt out any time.
How to use this (and the two resources next to it)
Three tools do three different jobs. The checklist identifies the tasks. The 100 day integration plan sequences them against your team's capacity. The integration playbook explains how to make and defend the hard decisions. Start here. A completed checklist is not proof of a successful acquisition, but a skipped one is a reliable way to break a good business.
The checklist
Integration starts here, not on day one
- Write down the integration thesis: what you are buying, and what has to stay true for it to work. Owner: the deal lead.
- Set expectations with the seller before the LOI (see the pre-close and seller transition plan): what changes, what does not, their role and timeline, what they have promised employees and customers. Owner: the deal lead.
- Read the data room for integration risk, not just deal risk: change-of-control and assignment clauses, key-person dependency, customer concentration, undocumented handshake deals. Owner: the deal lead, with finance.
- Name the critical people you must keep, and why. Build the retention map now. Owner: HR, with the general manager.
- Choose the operating model: preserve and strengthen, selectively integrate, or substantially consolidate. Decide it on purpose. Owner: the president.
- Freeze the opening baseline: people, customers, profits, cash. You cannot protect what you never measured. Owner: the finance lead.
- Draft the day 1 plan and the first 100 days before you sign. Owner: the integration lead.
Do not break the business you just bought
- Confirm payroll, banking, cash access, and signing authority are live on day one (the full day 1 readiness checklist). Owner: the finance lead.
- Set up systems access: who has what, and what nobody should touch yet. Owner: the systems lead.
- Run the first all-hands. Say what you know, what you do not, and what happens next. Owner: the president.
- Sequence the communications cascade: employees first, then customers, then vendors. Owner: the integration lead.
- Hold the line on change. In the first weeks, leave alone anything that is working. Owner: the general manager.
- Open the risk and issue log. One issue is never just one issue, so log what sits under each one. Owner: the integration lead.
Keeping the key employees is everything if you want to keep the key customers
Deeper dives: employee retention after acquisition and customer retention after acquisition.
- Run stay conversations with the critical few. Not everyone, the few who hold the business. Owner: the general manager.
- Put targeted retention in place where it matters. Blanket retention wastes money; missing the key person loses the business. Owner: HR.
- Leave the compensation plan for top producers alone until you have modeled the change. Change it carelessly and they walk. Owner: the sales leader, with HR.
- Give org clarity fast. Decide: keep their management layer, or flatten it into yours. Owner: the president.
- Transfer the knowledge in one person's head before that person can leave. Owner: each function lead.
- Honor or renegotiate the seller's verbal promises on purpose, not by accident. Owner: the deal lead.
Relationships still matter in a digital world
- Protect the top accounts. Transfer account ownership before the relationship holder leaves. Owner: the sales leader.
- Watch what made them loyal: service levels, looser credit terms, handshake pricing. Changing these quietly loses customers. Owner: the sales leader.
- Decide cross-sell timing. Push too early and you risk the relationship you paid for. Owner: the sales leader.
- Check contracts for change-of-control consent before you assume they carried over. Owner: the finance lead, with counsel.
- Set early warning signals on churn and watch the opening customer cohort separately from new sales. Owner: the sales leader.
Where the acquisition quietly loses the value you paid for
- Compare actuals to the opening baseline every month, not the budget you inherited. Owner: the finance lead.
- Watch gross margin, labor productivity, collections, and integration spend. Owner: the finance lead.
- Keep a synergy ledger: separate what is bankable from what is aspirational, and track who owns each. Owner: the finance lead.
- On vendors, do not move the company you bought onto your master agreement if it has the better rate. Find out why it got that rate first. Owner: the purchasing lead.
- Protect working capital and collections through the transition. Owner: the finance lead.
Now you improve
- Capture the synergies against the ledger. Assign owners. Separate real savings from cost shifts. Owner: the finance lead.
- Run the operating improvements the thesis promised, in sequence, against capacity. Owner: the operations lead.
- Lead the change with ADKAR. Expect the valley of despair, the dip in performance and morale before it climbs, and hold your nerve through it. Owner: the integration lead.
- Set the governance rhythm and the scorecard that warns you before the P&L does. Owner: the president.
- Declare integration complete against clear exit criteria, and transition to normal operations. Owner: the integration lead.
Work it with your team
The editable spreadsheet puts an owner and a status on every line and adds the opening baseline tab. Integration takes a team that is aligned to pull it off.
Decisions on this topic
The specific calls operators face inside this part of the integration. Each has its own page, with the tension laid out and a way to decide.
- Why one issue is never just one issue. A lost account, a late job, a quality miss: usually a symptom of a deeper integration fault nobody traced.
Questions
What is post-merger integration?
Post-merger integration, often shortened to PMI, is the work of combining two businesses after an acquisition closes: the people, customers, operations, systems, and finances. It is where most acquisitions succeed or fail, because closing only transfers ownership.
What should a post-merger integration checklist include?
At minimum: a pre-close plan and seller expectations, a day 1 readiness list, a people retention plan, a customer continuity plan, a profit and cash baseline to measure against, a change management approach, and clear exit criteria. This checklist covers all of those, organized by phase.
How long does post-merger integration take?
The first 100 days stabilize the business. Value creation runs through the first year and sometimes longer. The right length depends on your operating model: preserving an autonomous business takes different work and time than consolidating overlapping operations.
Does one checklist fit every acquisition?
No. The tasks are consistent, but the emphasis changes with your approach. Preserving a business with a valuable local identity is not the same job as consolidating two overlapping operations. The checklist flags where that choice changes the work.