Pasted from <http://scn.sap.com/thread/1985450>
This error refers to tax customizing so you should check what assingments you have in R/3 and then replicated on CRM. You can use transaction CRM_TAXCUST_VALIDATE to check the tax errors both in customers and materials. Then, according to the missing entries you will see on the transaction I told, you should check in R/3 tables TSKM and TSTL (used for materials). In table TSTL you have all the customizing made on R/3 transaction OVK1 and in table TSKM you´ll find the customizing made on transaction OVK4. The entries made there for your country should be the same ones made in CRM. The customizing path is the following: SPRO>CRM>Basic Functions>Taxes>Basic Settings>Tax Types and Tax Groups>Assing Tax Groups to SAP ECC Tax Classifications (Products) Here you have to enter the combination of: COUNTRYTAX TYPETAX GROUPTAX SEQTAx CL (which you should be able to fullfill after checking the R/3 tables
Pasted from <http://scn.sap.com/thread/1985450>
