Nobody knows for sure just how much tax return fraud is committed, but the amount is rising fast. According to the U.S. Treasury, the number of identified fraudulent federal returns has increased by 40 percent from 2011 to 2012, an increase of more than $4 billion. Ten years ago, New York state stopped refunds on 50,000 fraudulently filed tax returns. Last year, the number of stopped refunds was 250,000, according to Nonie Manion, executive deputy commissioner for the state's Department of Taxation and Finance.