SAP has provided a workaround for customers who do not want to use Vertex. - However this is for US V2.
Certain workaround while activation of Best practice required to be done & post activation of best practice, Taxation config needs to be done manually.
For more info please refer to SAP NOTE 2247743
2247743 - SAP Best Practices for S/4HANA, on premise edition (USA) (USV2)
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4. Activation guidance without the VERTEX Integration
In case you need to install the SAP Best Practices S/4HANA on premise edition USV2 without the VERTEX integration you may use the following attached documents:
a) S4HANA 1511 OP BP USV2 Activation guidance without VERTEX integration.docx
Provides how to skip the Vertex check errors and remove the external tax configuration where required.
b) S4HANA Manual tax configuraiton amendments (without Vertex Integration)– Provides the necessary tax configuration and sample tax rates in order to run the test scripts in sandbox. Please note that this document does not provide the correct tax rates for productive systems. You consultant needs to check and modify the manual configuration steps and the tax rates as per the needs of your customer.