MIGRATION RECONCILIATION AND CUTOVER WORKSHEET
Horizon Dynamics | Version 1.0 | 27 September 2026
Companion guide: https://www.horizon-dynamics.tech/blog/legacy-system-modernization-playbook

A planning aid for an agreed migration scope. Copy the repeated blocks for each
entity or check. Blank evidence is unresolved, not a pass.

MIGRATION / OWNERS / REHEARSAL
Old system:
New system:
Business decision owner:
Technical migration owner:
Data owners:
Rehearsal environment and date:
Dataset version / extraction cutoff / time zone:
Sensitive-data handling agreed:

1. SCOPE AND SOURCE OF TRUTH
Included entities and historical period:
Excluded records and approved reason:
Source of truth for each record or field during coexistence:
Which system accepts new writes before and after cutover?
Ongoing synchronisation direction and schedule:
Dependencies: documents, scheduled jobs, exports, reports and external actions:

2. MAPPING - REPEAT PER ENTITY
Entity:
Source identifier -> target identifier:
Required parent/child relationships:
Transformations and status mapping:
Required fields and treatment of missing values:
Duplicate and amended-record rules:
Deletion or archival behaviour:
Owner who approves this mapping:

3. RECONCILIATION CHECK - REPEAT PER CHECK
Check identifier and purpose:
Dataset / sample period / population:
Source query or export reference:
Expected result and permitted difference, if justified:
Target query or result reference:
Actual result:
Record-level sample evidence:
Related documents accessible to the correct roles:
Status: not run / passed / failed / accepted exception:
Difference, cause and owner:
Evidence reference (keep private if it contains customer data):
Reviewer and review date:

4. EXCEPTION AND RETRY SCENARIOS
Agree expected behaviour before testing:
[ ] Same import repeated without source changes.
[ ] Source record amended between two imports.
[ ] Two records share a name but have different stable identifiers.
[ ] Missing or invalid parent/customer reference.
[ ] Cancelled or partially completed transaction.
[ ] Attachment/document linked to a historical record.
[ ] Out-of-order update or delayed event.
[ ] Sync fails partway through and resumes.
[ ] User with limited access tries to open a migrated record/document.
[ ] Boundary date, time zone or currency transformation.
For each: expected result / observed result / evidence / status / owner.

EXAMPLE FAILURE
Two orders have equal values and their customer references are swapped during
mapping. Counts and totals match, but each order belongs to the wrong customer.
A relationship check against stable source references must reveal the error.
This is why aggregate totals alone are not an acceptance test.

5. CUTOVER GATES
For each gate: pass condition / evidence / reviewer / decision.
- Critical workflows, exceptions and permissions tested:
- Required data and relationships reconciled:
- Unresolved exceptions explicitly accepted or blocking:
- Final write/freeze/sync procedure rehearsed:
- Recovery and backup evidence reviewed:
- Support owners can see failures and recover missed work:
- Users informed and operating instructions available:

6. RECOVERY DECISION
Trigger and person authorised to pause or reverse the rollout:
Which data has been created or changed since the switch?
How are new writes, external actions and documents handled during recovery?
Rehearsed recovery procedure and evidence:
Recovery constraints and accepted consequences:
No assumption that switching traffic back reverses business transactions.

7. GO / NO-GO RECORD
Decision: proceed / delay / reduce scope:
Decision owner and timestamp:
Evidence reviewed:
Accepted exceptions and owners:
Next verification point:

Discuss the transition: https://www.horizon-dynamics.tech/contact?source=migration-template
You may adapt this template for your own project planning.