The flap over Apple’s (AAPL) corporate tax strategy might seem like a snoozer, until you consider who makes up the difference for Apple’s shrunken tax payments. That would be you, dear taxpayer.

Apple is in the crosshairs as Congressional investigators claim the company used audacious accounting methods to avoid paying tax on at least $74 billion of income during the past three years. Apple did nothing illegal but it shifted money among various overseas entities in a way that essentially left billions in income under no nation’s jurisdiction. Senate Democrats initiated the investigation as legislators are beginning the spade work for what may ultimately be an ambitious effort to overhaul the entire U.S. tax code.

Apple is the latest poster child for a tax system many experts say is routinely abused by those with the means to hire tax lawyers and accountants able to fully exploit hundreds of loopholes. General Electric (GE), Microsoft (MSFT), Google (GOOG) and many other companies have faced similar charges. The real problem isn’t any one company’s tax strategists, however, but lawmakers who have shredded the tax code into a leaky mess.

The victims

The victims, meanwhile, are ordinary taxpayers who fund most of the federal government. During the 1950s, individual income taxes typically accounted for about 60% of the government’s tax revenue, with corporate taxes covering the other 40 percent. By 1970 individuals paid 73% of all taxes. By 1990 it was 83 percent, with the peak coming in 2009, when corporations claimed steep losses and individuals paid 87% of all taxes. By 2012, that had drifted down to 82%, with corporations paying 18%.

Despite that shrinking share of the nation’s tax payments, the business lobby routinely claims taxes on U.S. corporations are too high because the official federal tax rate of 35 percent exceeds the rate in every other developed nation. But after credits and deductions, most U.S. companies pay an effective tax rate that’s considerably lower, ranging from 23 to 35 percent.

[Related: Sorry, Tim Cook, U.S. Tax Law Isn't a Big Economic Drag]

Some large U.S. multinationals are able to lower their taxes further by moving money among divisions based in different countries, to take advantage of the lowest tax rates. A 2011 New York Times story explained how GE earned a $14.2 billion profit in 2010 yet paid no federal income tax in the United States. Companies such as Apple that sell software or other types of intellectual property can take advantage of other loopholes that allow wide latitude for where they claim profits, and therefore pay taxes.