When entering an Expense (Purchase Invoice), we have the option to assign a Cost Category. The Cost Category determines, on the one hand, the percentage of VAT that may be reclaimed and the percentage that may be applied as business costs. A Cost Category is also linked to a General Ledger account, to which the costs will ultimately be posted.
It may happen that for a specific reason you want to post the costs to a different General Ledger account than the General Ledger account assigned to the Cost Category. To do this, proceed as follows:
As you can see, the Rent Cost Category is selected for entering the Expense.
Now if we click on the Details icon 
, the Details window will appear
We now see the General Ledger account that is assigned to the relevant Cost Category, but we are also able to select a different General Ledger account to which the costs will be posted when the Expense is Finalized.
Press 
to save changes within the Details.