Readers of this column know that the federal government wastes a lot of taxpayers’ money. How much? Last year, by its own estimate, the government sent out $100 billion in improper payments. In fact, as Rep. John Mica explained, “It’s over $100 billion each of the last five years. That’s a staggering half a trillion dollars in improper payments.”

The improper payments peaked at $121 billion in 2010. Last year Medicare topped the charts with $50 billion in improper payments. Medicaid was responsible for $14.4 billion in improper payments, and unemployment insurance $6.2 billion. Improper payments under the earned income tax credit came to $14 billion alone, a full 24 percent of all the payments. And so on, with major federal agencies and programs all contributing. But as it turns out, the $100 billion likely understates the problem, subject of hearings this week before the subcommittee on government operations of the House Oversight and Government Reform Committee.

IRS boss John Koskinen told the subcommittee that the rate of improper payments was unacceptable and that the government needed to do “whatever we can,” to fix it. Thus spake the powerful man who is unable to find the missing emails of Lois Lerner and six of her IRS associates.

White House deputy budget director Beth Cobert told the committee “We have taken an aggressive approach to attacking waste, fraud and abuse within federal agencies, and we will continue to seek out new and innovative tools to help us in this fight.” Actually, they haven’t and won’t, according to Beryl H. Davis, financial management boss at the General Accounting Office. Davis told the subcommittee that “the federal government is unable to determine the full extent to which improper payments occur and reasonably assure that appropriate actions are taken to reduce them.”

So here’s the real deal for embattled American taxpayers. The federal government remains an engine of waste, fraud and abuse on a colossal scale. The $100 billion in improper payments is the latest evidence that federal government agencies remain essentially unreformable.