No unique tax date for company code &1 ID &2.

What causes this issue?

In company code &V1& time-dependent tax codes have been activated. This
requires that a tax date is also set for the expense and revenue items
with a tax code. If this date was not set by the program called up, the
system attempts to determine and set from the associated tax items.
In this case, there are company codes &V1& and tax codes &V2& with a
different tax date which means that it is not possible for an automatic
transfer of the tax date to the associated expense/ revenue items.

System Response

The posting cannot be executed.

How to fix this error?

If you use the standard program, enter a message for SAP. If you execute
the posting by API / BAPI call, also fill the field tax date in the
revenue / expense item.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.