No exc. tax % found for mat. & and special indicator & - normal rate used

What causes this issue?

The system has determined an indiactor for a special tax rate. This
rate is not maintained in the tax rate table so that the system now use
the normal rate for this material.

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?

If the system should use a special rate for this material this rate
have to defined for the special indicator.

Error message extract from SAP system. Copyright SAP SE.