I started with phased vs big-bang and felt pretty confident there, landed on phased with a parallel run period which they seemed to like.
Structure your answer around a phased migration lifecycle: discovery and planning, design and mapping, build and testing, cut-over, and post-migration support. Emphasize data integrity, risk mitigation, and stakeholder alignment at each phase, and tie decisions back to business outcomes like payroll accuracy and compliance.
Pro tip: Show that you understand payroll is a high-stakes, compliance-heavy domain by prioritizing parallel runs and reconciliation over speed. Mention that you'd define a 'no-go' criteria for cut-over and get explicit sign-off from Finance, HR, and Legal before proceeding.
Assess the legacy system's data model, volume, quality, and dependencies; define migration scope, success criteria, and a phased approach (e.g., pilot then full rollout). Align with stakeholders on timeline, budget, and compliance requirements.
Create a detailed field-to-field mapping between legacy and new schemas, including transformations and default values. Define validation rules (e.g., checksums, record counts, business logic checks) and plan for data cleansing and enrichment.
Develop migration scripts and ETL pipelines, then run multiple test migrations in a staging environment. Perform parallel payroll runs to compare outputs and reconcile discrepancies before go-live.
Choose a low-risk cut-over window (e.g., after a pay cycle) and execute a detailed runbook. Define rollback triggers, a tested rollback procedure, and a communication plan for contingencies.
Monitor system performance and data integrity post-cut-over, provide hypercare support, and gather feedback. Communicate progress, risks, and outcomes regularly to all stakeholders through a RACI matrix and status reports.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.