INVOICE UNPLANNED DELIVERY COST IDOC

To post unplanned delivery cost using INVOIC01 we referenced OSS Note
800866. We continued to have issues with determining the tax jurisdiction
code and received this response:
I have done a detailed analysis and the
solution I propose is to use the FM 'EXIT_SAPLMRMH_014'. The options
are:
1. If the field TXJCD is blank in the idoc and if the tax code for the
unplanned delivery cost is same in invoice item and in the refered
PO item, then you can fill E_RBKPV-TXJCD_BNK from the PO item in the FM
'EXIT_SAPLMRMH_014'.
2. If the tax code for the unplanned delivery cost is not same as the
tax code in invoice item or in the refered PO item, you can find the
TXJCD from the tax condition's data for the tax code and copy it to
E_RBKPV-TXJCD_BNK within the user exit.
3. If the field TXJCD is filled in the idoc, you can fill the
E_RBKPV-TXJCD_BNK in the user exit from here.
We choice option 3 and we are successfully posting unplanned delivery cost
using INVOIC01.