Enter a valid tax code

What causes this issue?

You have either specified a tax account in the customer/vendor items
which does not match the one specified in the G/L account or the tax
code specified has not been defined in Customizing.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

INCLUDE FI_NA_CUST

Error message extract from SAP system. Copyright SAP SE.