Technically the Gen. Posting Type is mandatory if you use Gen. Bus. / Gen. Prod. / VAT Bus. / VAT Prod. Posting Group.
You cannot use the Gen. Posting Type without using groups and you cannot use groups without the Gen. Posting Type.
Whenever NAV/BC needs to calculate VAT and need to distinguish whether it's a sales VAT or a purchase VAT then the Gen. Posting Type is needed. So basically ... if you have to use Gen. Bus. / Gen. Prod. / VAT Bus. / VAT Prod. Posting Groups you also need to have the Gen. Posting Type.
In "documents" (Sales invoice, purchase invoice) the Gen. Posting Type comes with the document. Also the Gen. / VAT Bus. Posting Group comes from the customer/vendor used in the header.
But the Gen. / VAT Prod. Posting Group has to come from the G/L Account that is to be used in the line.
If you use itmes instead of G/L accoutns then the Gen. Postign Type is needed to distinguish whether we need to pull sales accoutns or purchase accoutns from the Gen. Posting Setup table.
That means that for all G/L accounts which you want to use in documents you need to have the Gen. / VAT Prod. Posting Group specified on the G/L Account ... and you need to have valid combinations of posting groups in the General Posting Setup and the VAT Posting Setup ... which doesn't necessarily mean that tax/VAT is calculated ... combinations can be set up in a way that no tax/VAT is being calculated.
And together with the Gen. / VAT Prod. Posting Group you need the Gen. Posting Type.
In journals the Gen. / VAT Bus. Posting Group need to be specified directly ... or taken over from the default values on the G/L Accounts ... but only if tax/VAT has to be calculated (this goes also for zero amount VAT Entries ... in case you need to report on this category ... like for sales amount / base for overseas revenue ... no VAT, but still the base amount has to be reported).
If the transactions has no VAT relevance, then you don't need groups and setup combinations and you don't need the Gen. Posting Type.
And yes, for most Balance accounts you don't need groups (setup combinations) and Gen. Posting Type whereas for most of the P&L accoutns (the ones you use directly in documents and the ones you use in journals and need to calcualte tax/VAT you should have default groups (and the setup combinations) and Gen. Posting Type
Hope this helps
Dirk
