No tax data exists (as yet)

What causes this issue?

You would like to display detailed information on taxes for a certain
document or line item. There is, however, no tax information available.

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 you enter the tax amounts manually, no amounts have been entered
previously.
If you want to have the system calculate the amounts ("*" in the tax
amount) and you have already entered tax-relevant G/L account items,
your company code is defined so that the parameters "Tax base is net
value" and "Cash discount base is net value" are both valuated with
"X". In this case, taxes can only be calculated after you have selected
"Post" for the document.

Error message extract from SAP system. Copyright SAP SE.