No, the CIS module isn't a requirement for Domestic Reverse Charge. If you process CIS manually you can continue to do so, but using the CIS module makes processing CIS easier.

The new tax codes needed for Reverse Charge are available in Sage 50 Accounts v26 and above.

If you already use the CIS module you must make sure you're using CIS v2, which is compliant with the new legislation. 

TIP: You can check that you've enabled CIS v2 by going to Help, then About. In the left column scroll down to Features Enabled then check it has Yes next to CIS v2.

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