Data mapping from the Source Data Set to the Target systems can get very involved subject to the amount of fields and the mismatches found, and how the cleaning or data transformation is physically actioned.

 Consider and select what tool you are comfortable working with e.g. A simple document  and manual edits in the Master Set, or more functionality with Excel, Google Sheets and SQL Server (SSMS) feeding automatic updates data back to the master set or low cost tools such Zoho DataPrep or Skyvia  are good.

Once complete initial sample testing should be actioned, before the main UAT Testing in the lead up to the Migration Go Live.

Such tools allow easier cleaning and transformations. There are enterprise priced tools  with wider functionality also.

Core Tasks for this Milestone:

A) Choose your mapping tool and/or Create a Simple Mapping Sheet to start

B) Match each field and consider business process priority.