The answer is they cost the same.
The difference is that the $2,100 check is classified as federal spending. And the tax break doesn't show up on the $3.6 trillion federal budget.
When politicians and others talk about the size of government and how to lower deficits, it's as if tax breaks don't exist.
But fiscal experts believe many tax breaks should be counted as spending.
After all, by handing out those tax breaks, the government is giving up hundreds of billions of dollars in revenue.
And in terms of policymaking, many tax breaks are the functional equivalent of cash. That is, the government uses them to achieve goals that could just as easily be achieved by issuing a check.
Examples abound. Congress wants to foster homeownership, so it lets homeowners deduct their mortgage interest. Lawmakers want to reduce greenhouse gas emissions, so they offer a tax credit to companies that produce biofuels such as ethanol or biodiesel.
Tax reform: Why it's so hard
The issue of so-called tax expenditures is of great importance today, as politicians and presidential candidates debate how to control government spending, which is a measure of how big government is.
"We should think carefully about how to measure it," said Donald Marron, director of the Tax Policy Center.
Indeed, if tax breaks that are "clear spending substitutes" were counted
http://money.cnn.com/2012/04/02/news/economy/government-spending/index.htm?iid=HP_LN

Realist - Everybody in America is soft, and hates conflict. The cure for this, both in politics and social life, is the same -- hardihood. Give them raw truth.