Which Brazilian Fraud is Bigger? Brazilian Ministry of Finance's Tax Fraud for Bribes Or Petrobras' Contract Skims?

The answer is - it's a close call.  Both will probably, at the current very weak exchange rate, come in around US$6 billion (20 billion reais).

Reuters reports that the tax fraud at the Ministry of Finance may be worth US$6 billion: "Brazilian authorities on Thursday said they uncovered a tax fraud scheme at the Finance Ministry's tax appeals board that may have cost taxpayers up to 19 billion reais ($5.96 billion)."  But Reuters further reports "Early on Thursday, police raided the offices of the tax appeals board in Brasilia, and the homes and offices of tax consultants and lawyers suspected of acting as intermediaries. They also raided the headquarters of Banco Safra SA , Brazil's eighth largest bank ..."  

The FT reports that so much was looted from Petrobras though, Petrobras cannot even account for the total looted, which is in the billions.  Forbes reports that the total cost exceeds at least $4.5 billion just for five of the involved construction companies that are seeking bankruptcy protection as a result.