I'm not entirely sure this is the complete answer but apparently if you click "Summarise Profit and Loss values" on the Trial Balance report it will revert profit and loss codes to this financial year only (but maintain total balances for balance sheet items). 

Hi

Have you sorted this.

After doing a year end process the balances in P&L Accounts are debited/credited out to the Balance Sheet under retaining profits.

At that point if you run a TB (or view on the Nominal list screen) then the P&L figure should be blank/zero.

When you say you have changed the year end date - how did you do this.

It should be an automatic change when doing a year end.

Best Regards

Ken

Thank you Ken for the reply. I think I've sorted it for what I need (which is a trial balance for my new financial year showing balance sheet values and profit and loss items for this year only). I now have a calculated profit and loss figure which I assume is added to each year from now on. I changed the year end date in settings/business settings/financial settings/accounting dates and VAT.