Clients that recently migrate in to NAV, often experience the above issue when posting transactions through documents – purchase/sale or through journals. NAV users may interpret this error in various ways and the easiest way to resolve this would be to define a “Gen. Posting Type” against the G/L account card.

However, before fixing this issue, it is very important to understand what is causing the issue and what is the right resolution to prevent this error from occurring.

When user’s setup a new G/L account, the “Gen. Posting Type” field should be filled in only for revenue and expense accounts where GST is involved. If the transaction will impact your BAS (GST Reporting) then this field must be populated with either Purchase or Sale. If not, then it must be blank.

The Posting Groups consists of “Gen. Bus. Posting Group”, “Gen. Prod. Posting Group”, “GST Bus. Posting Group” and “GST Prod. Posting Group”. If the “Gen. Posting Type” field is defined, then we need to define the Posting Groups to correctly calculate the GST and post correct transactions to general and sub-ledger entries. If the transactions do not involve any GST, then the “Gen. Posting Type” and Posting Groups must be “blank”.