When you are running S4HANA conversion, this will include financial data conversion. For compliancy reasons the FICO business will demand you run reports before and after the conversion to show that the data is converted ok.
To structure these checks the DTV tool (data transition validation tool) was developed by SAP.
How to install the DTV tool
Master note for the DTV tool is 3117879 – DTV Tool – Central Note.
DTV tool can be used for S4HANA 2021 and higher as target system. There is no installation needed there.
For the source system you need to be on the right support package or install via TCI delivery note 3103342 – DTV Tool Initial Delivery.
Technical reference blog from SAP: link.
How to run the DTV tool
Start of the tool is transaction code DVF:
The detailed steps are described high level in this SAP blog.
All detailed steps (including how to setup connections to source system) are explained in the SAP help file for the DTV tool.