Merger and acquisition integration Gantt chart with Day 1 and 100-day review
An editable post-deal integration Gantt chart: integration office, Day-1 readiness, finance, HR and payroll, systems, contracts and communications, with milestones for Day 1 and the 100-day review.
What the merger and acquisition integration gantt chart with day 1 and 100-day review process is
Integration is hard to schedule because the work belongs to different people and most of it cannot start until the same few things are settled. The integration office needs owners before any workstream can plan, finance and HR need the other company's practices mapped before they can change them, and everyone needs one Day 1 that employees, customers and suppliers can recognise. This page covers the operational side only: who does which job, in what order, and what waits for what. It does not cover deal terms, valuation or legal strategy.
This template has four groups: Governance and communications, Finance and HR, IT and systems, and Operations and contracts. It has 22 tasks and three milestones. "Set up integration office" (3 working days) is the only starting task and "Agree workstream leads and priorities" (4) follows it. Five preparation tasks then run side by side: "Plan Day-1 communications" (3), "Map finance close and reporting differences" (5), "Map payroll and benefits differences" (4), "Inventory systems and access rights" (5) and "List contracts needing notice or transfer" (6). "Run Day-1 readiness review" (2) waits for all five, and the "Day 1" milestone waits for the review.
After Day 1 the groups stop waiting for each other and start overlapping. "Send Day-1 notices to customers and suppliers" (2) is a dead end by design: nothing downstream needs it. In Finance and HR, "Set up combined management reporting" (8) leads to "Run first joint month-end close" (5) and then "Hold first synergy checkpoint review" (1), while "Align payroll and benefits administration" (10) runs beside it. In IT and systems, "Migrate email and collaboration accounts" (8) comes before "Consolidate core finance and HR systems" (25), which also waits for payroll alignment and starts 4 days after the account migration starts. "Core systems consolidated" is the milestone that closes the group.
Operations and contracts is mostly administration. "Harmonise supplier and site arrangements" (12) and "Update legal entity and contract records" (10) overlap, with the records task starting 4 days after the first starts. This is scheduling only: the chart shows when the admin is meant to happen, not what the contracts say. "Hold weekly integration status reviews" (60) runs from Day 1 and is linked finish-to-finish to "100-day review", so the reviews stay on the plan until the review itself. "Hand over to business as usual" (3) comes last. Durations are illustrative, and the real 100 days will not match 60 working days of status reviews unless you set them to.
A timeline schedules integration work. It is not legal, tax or financial advice, and it does not make anything compliant, legally valid or secure. For the method behind a change of this size, see the change management Gantt chart at /templates/change-management-gantt, the process implementation Gantt chart at /templates/process-implementation-gantt and the general project Gantt chart at /templates/project-gantt-chart.
What this flowchart covers
In this template
- Four groups, Governance and communications, Finance and HR, IT and systems and Operations and contracts, with 22 tasks and three milestones: "Day 1", "Core systems consolidated" and "100-day review".
- A readiness gate: "Run Day-1 readiness review" waits for "Plan Day-1 communications", the finance and payroll mapping, "Inventory systems and access rights" and "List contracts needing notice or transfer".
- Overlapping post-Day-1 work: "Consolidate core finance and HR systems" waits for "Align payroll and benefits administration" and starts 4 days after "Migrate email and collaboration accounts" starts.
- Contract administration as scheduling only: "Update legal entity and contract records" starts 4 days after "Harmonise supplier and site arrangements" starts.
- Review points: "Hold first synergy checkpoint review" after the first joint close, and "Hold weekly integration status reviews" finishing with "100-day review".
When to use this template
- You are planning the first months after a deal closes and need finance, HR, IT and operations leads to agree one order of work.
- You want to see which preparation task decides the date of Day 1 and what each group can start once it has passed.
- The integration office needs a timeline to review each week, and a date for the 100-day review to compare with the date you need.
- You want a reusable skeleton that each acquisition can adapt, with its own workstreams, owners and durations.
The plan, task by task
Every task in the chart with its length in working days and what it waits for. A dependency is a step number; SS is start-to-start, FF is finish-to-finish, and +n is a lag in working days.
| # | Task | Group | Working days | Depends on |
|---|---|---|---|---|
| 1 | Set up integration office | Governance and communications | 3 | |
| 2 | Agree workstream leads and priorities | Governance and communications | 4 | 1 |
| 3 | Plan Day-1 communications | Governance and communications | 3 | 2 |
| 4 | Map finance close and reporting differences | Finance and HR | 5 | 2 |
| 5 | Map payroll and benefits differences | Finance and HR | 4 | 2 |
| 6 | Inventory systems and access rights | IT and systems | 5 | 2 |
| 7 | List contracts needing notice or transfer | Operations and contracts | 6 | 2 |
| 8 | Run Day-1 readiness review | Governance and communications | 2 | 3, 4, 5, 6, 7 |
| 9 | Day 1 | Governance and communications | Milestone | 8 |
| 10 | Send Day-1 notices to customers and suppliers | Governance and communications | 2 | 9 |
| 11 | Set up combined management reporting | Finance and HR | 8 | 9 |
| 12 | Run first joint month-end close | Finance and HR | 5 | 11 |
| 13 | Align payroll and benefits administration | Finance and HR | 10 | 9 |
| 14 | Migrate email and collaboration accounts | IT and systems | 8 | 9 |
| 15 | Consolidate core finance and HR systems | IT and systems | 25 | 13, 14SS+4 |
| 16 | Core systems consolidated | IT and systems | Milestone | 15 |
| 17 | Harmonise supplier and site arrangements | Operations and contracts | 12 | 9 |
| 18 | Update legal entity and contract records | Operations and contracts | 10 | 17SS+4 |
| 19 | Hold first synergy checkpoint review | Governance and communications | 1 | 12 |
| 20 | Hold weekly integration status reviews | Governance and communications | 60 | 9 |
| 21 | 100-day review | Governance and communications | Milestone | 16, 18, 19, 20FF |
| 22 | Hand over to business as usual | Governance and communications | 3 | 21 |
How it works
Set up the office and the owners
Keep "Set up integration office" and "Agree workstream leads and priorities" at the start, since every other task waits for them. Replace the durations with how long your teams really need.
Run the preparation tasks together
The five tasks after the priorities all feed "Run Day-1 readiness review". Add your own preparation tasks, and keep the review as the single gate before "Day 1".
Start the workstreams on Day 1
Finance, payroll, accounts and contract admin all follow "Day 1". Move a dependency earlier only if the work can safely begin before the review.
Use lags where work truly overlaps
"Consolidate core finance and HR systems" and "Update legal entity and contract records" are linked start-to-start with a lag of 4 days. Change the lag, or make the link finish-to-start, if your teams cannot overlap.
Place the checkpoints
"Hold first synergy checkpoint review" is a scheduled meeting after the first joint close, not a financial model. Add more checkpoints as tasks and set the length of "Hold weekly integration status reviews" to fit your plan.
Add owners, share and export
Put the responsible person in People, share the chart with the integration office and workstream leads, and export a PDF or CSV when you need a copy.
Frequently asked questions
How long does post-deal integration take?
It depends on the size of the deal, the systems involved and your approach. The template uses illustrative working-day lengths. Replace them with your own and compare the finish date of "100-day review" with the date you need.
Does this chart give legal or financial advice?
No. It schedules the operational work after a deal. Legal, tax, accounting and employment decisions follow your own advisers and policies, and nothing here makes an integration compliant or legally valid.
Why is Day 1 a milestone after a readiness review?
Because Day 1 is a date other people plan around. Making it wait for "Run Day-1 readiness review" shows how late it would move if a preparation task ran long.
Can I track synergies in the chart?
Only as scheduled review points, such as "Hold first synergy checkpoint review". The chart does not model savings or costs. Keep those figures in your own finance tools.
What if one integration team is bigger than the others?
Add tasks to its group, or split the group in two. For a wider change programme, see /templates/change-management-gantt, and for the dependency method see /guides/gantt-chart-dependencies.