(AP) Tax Day is a dreaded deadline for millions, but for nearly half of U.S. households it's simply somebody else's problem.

About 47 percent will pay no federal income taxes at all for 2009. Either their incomes were too low, or they qualified for enough credits, deductions and exemptions to eliminate their liability. That's according to projections by the Tax Policy Center, a Washington research organization.

Most people still are required to file returns by the April 15 deadline. The penalty for skipping it is limited to the amount of taxes owed, but it's still almost always better to file: That's the only way to get a refund of all the income taxes withheld by employers.

In recent years, credits for low- and middle-income families have grown so much that a family of four making as much as $50,000 will owe no federal income tax for 2009, as long as there are two children younger than 17, according to a separate analysis by the consulting firm Deloitte Tax.

Tax cuts enacted in the past decade have been generous to wealthy taxpayers, too, making them a target for President Barack Obama and Democrats in Congress. Less noticed were tax cuts for low- and middle-income families, which were expanded when Obama signed the massive economic recovery package last year.

The result is a tax system that exempts almost half the country from paying for programs that benefit everyone,...