The EU has no need to seek accountants to audit their budget - the European Court of Auditors was established in 1994 for that very purpose. Reports saying that the auditors "refused to sign off the accounts" have appeared every year since the formation of the ECA but are slightly misleading. The ECA agree the EU accounts are reliable, i.e. the accounts accurately recorded all transactions, assets and liabilities, but they will not endorse all of the spending that has taken place, not primarily for reasons of fraud (although fraud obviously does exist - some examples having been cited by
youngmafbog - and which accounts for less than 0.1% of the total budget) but that some transactions have violated regulations and/or contractual conditions.
http://www.europeanvoice.com/article/2008/11/e u-fails-its-spending-audit,-again/63002.aspx