Start in Prod. codes and go through the remaining budget per production code. Then open the code that deviates, and use the Totals tab to see exactly what the final forecast consists of.
How to do it
Go to Prod. codes and sort by Rem. budget (may be called Rem. Cost price estimate in your project). If the column isn't shown, turn it on under Columns.
Look first at the red items. These are overruns, and that is where the error most often is.
Open the production code and choose Totals in the panel on the right on the General tab. It shows purchases, change orders and expected additions, and what they are linked to.
Go through the Expected Addition tab on the code and look for additions that are left over or entered twice. The Link column shows what they are linked to.
Correct or delete what is wrong, and check the total again.
Typical errors
The contract value covers two buildings, but only one is contracted.
A contract sits on a production code that shouldn't have cost.
Installments or invoices are registered as separate purchases, so the cost is counted twice.
An expected addition is left over after the contract or change order it related to has been registered.
Good to know
Don't hide a negative remaining budget with transactions. You then lose track of where the deviation really is.