During system implementation, parallel testing is used to verify that critical payroll processes function correctly by running both the old and new systems side-by-side before full migration.

• A. Compliance testing
• B. Back-up testing
• C. Ongoing testing
• D. Parallel testing

Answer: (D)

Parallel testing validates a new payroll system by running it alongside the existing system and comparing outputs to ensure the new setup produces the same results as the current one before full migration. By processing payroll with the same data in both systems, you can verify calculations, tax rules, deductions, and reporting are consistent, catching any data conversion issues or calculation discrepancies before going live. This approach provides real-world validation of end-to-end processes and interfaces, helping protect accuracy and regulatory compliance during the transition. It’s distinct from backup testing (which checks recovery procedures), ongoing testing (which focuses on continual validation after deployment), and compliance testing (which ensures regulatory requirements are met).