same invoice multiple tax setup in nav 5

We are using nav 5 Singapore version and no plans to upgrade. Now we want to setup a kind of provisional tax like if tax is 20% in that GST 18% and provisional tax 2%..Basically dual  tax in single invoice..  In nav 5, i can see only GST posting group. Please advise how to setup this. 

  • Hi ,

    You need to loot at Item VAT Product Posting Group . The Setup of that and the Matrix of the Customer's Busines VAT Posting Group will define the VAT (GST)

    Persuming you are dealing W/ GST as VAT.