SAP Message /SAPPCE/DPCM1082 - You cannot change the tax code from &1 to &2

Diagnosis
You have changed a non-deferred tax code to a deferred tax code or viceversa. Postings already exist in the down payment chain for the previoustax code.

System Response
You can only change a non-deferred tax code to a deferred tax code ifthe cumulative invoice amount equals zero.

Procedure
Choose another tax code or reverse the already existing partialinvoices.