100-Day Post-Merger Integration Plans: What Should They Cover
In this section, the 100-day plans for HR, IT, Finance, Sales, Communications, Legal, and the IMO cover five areas that typically should be addressed in a successful post-merger integration:
- System consolidation. Select and consolidate one ERP, CRM, payroll system, chart of accounts, HRIS, and service desk. Complete system selection, data mapping, migration, validation, and legacy-system decommissioning.
- Policy harmonization. Align PTO and holiday schedules, 401(k) match and vesting, severance, remote-work policies, contract templates, and approval authority.
- Synergy realization. Track cross-selling, vendor savings, license consolidation, headcount, and stranded costs. Record realized synergies and report variances against the deal model.
- Business process stabilization. Run consolidated month-end close, payroll, financial reporting, and other recurring processes. Resolve exceptions quickly, refine processes before the next cycle, and confirm critical operations work reliably in the combined environment.
- Organizational health and culture. Communicate frequently, track customer and employee sentiment, monitor early attrition by team, manager, and location, and assess cultural integration through surveys and listening sessions.
A properly phased, complete integration looks like the 100-day post-merger integration workstream plans below.
| Workstream | Deliverable / File | Summary |
|---|---|---|
| Human Resources | 100-Day Human Resources Post-Merger Integration Plan | Takes the people integration to integration complete — finishing HRIS migration, harmonizing benefits and compensation, completing org design, and validating headcount synergies |
| Information Technology | 100-Day Information Technology Post-Merger Integration Plan | Covers rationalizing the application portfolio, consolidating infrastructure, migrating data, decommissioning duplicate systems, and locking in targeted IT synergies |
| IMO | 100-Day Integration Management Office Post-Merger Integration Plan | Guides the integration from execution to close-out, ensuring disciplined governance, accountability, and a successful transition to business-as-usual |
| Communications | 100-Day Communications Post-Merger Integration Plan | Sustains the narrative momentum built on Day 1 — managing the ongoing cadence of employee updates, customer communications, brand transition milestones, and media monitoring |
| Finance | 100-Day Finance Post-Merger Integration Plan | Takes the combined entity from a functioning Day 1 financial infrastructure to a fully integrated one — completing combined financial closes and validating synergies |
| Sales | 100-Day Sales Post-Merger Integration Plan | Stands up the unified sales organization, launches cross-sell programs, and migrates systems to a single CRM. |
| Legal | 100-Day Legal Team Post-Merger Integration Plan | Completes the post-close legal work — contract novations, legal policy and process standardization, and consolidating legal teams |