You can already check this when you design your P&L report(s) using the 'Validate' button. the design of a P&L may not necessarily include all the P&L report categories depending on what that particular statement is designed for, similarly at the time you run the report its possible to exclude accounts based on cost centre or departmental filtering. The key part to financial statements in 200c is that you use the validate button at the design state to ensure you have included all the categories just once unless you have a valid reason not to.

Thanks for posting this idea.  As Geoff Turner mentions, its not possible to create a nominal account without specifying a report category.  This differs from Sage 50 where the chart of accounts is held separately from the nominal accounts, so its possible to have a nominal account that's not included in the chart of accounts and subsequently not included in management reports.

Is it possible to provide an example of when you've found this to be a problem?

Since the P&L report always includes all P&L accounts, and all NL accounts have to have a report category, the only way accounts would be missing is if you've selected specific cc's/dept's.  And the system can't tell if an account "should be" P&L or B/S. (Usual disclaimer - this is Sage 200 professional, Sage 200 Education may be different!)

a heartfelt this would be good