:o)

or '(negative) effect on the accounts' or 'accounting impact' etc depending on context

'bilanzielle Belastung' can mean lots of things in practice. It may refer specifically to the balance sheet, but can also refer to the accounts in general or specifically to profit and loss:

'Bei einem Umsatz von 7,3 (8,0) Mrd. € steuerte die Schaden- und Unfallrückversicherung 289 (905) Mio. € zum Ergebnis der Rückversicherung im ersten Halbjahr bei; von diesem Betrag ist die bilanzielle Belastung von 750 Mio. € aus der Reservestärkung bereits abgezogen'
http://www.munichre.com/

It can also refer more generally to whether or not items are reflected in the financial statements, rather than to the actual substance of specific charges or amounts:

'Die Vorteile für Arbeitgeber...Keine bilanzielle Belastung'
http://www.gerling.de/de/MaklerNet/content/Vertriebspartner/...

In keeping with this, it does not necessarily imply a charge or liability and can refer to the presentation of assets or items which are beneficial in financial substance if, for example, they're hanging around the balance sheet where you don't really want them to be seen:

'In Wirklichkeit ist das Grundstück aber eine bilanzielle Belastung für den Käufer, weil er in seiner Bilanz einen finanziellen Gegenwert darstellen muss'
http://www.havelland.de/Presse/2003/021003.htm

In this case, it could be referring to minimising the actual financial effect of a specific item, but 'Gutachten' sounds more like legal/accounting/tax advice taken to achieve/avoid presentation of a transaction in a particular way ie keep it out of the accounts. As always, context is everything...