Sandra Block | February 14, 2010

Underpay your taxes, and you could receive a sternly worded letter from the IRS, with ominous references to "interest," "penalties" and possibly, "incarceration." But if you overpay, it's unlikely that the IRS will send you a check or even a thank-you note. It's your responsibility to claim all the credits and deductions available to you. Here's a look at some new tax breaks that could cut your 2009 tax bill:

Home buyer tax credit

This tax credit was originally intended for first-time home buyers, but that's no longer the case. Under legislation signed in November, two types of home buyers qualify for a tax credit on their 2009 returns:

- Home buyers who haven't owned a primary residence for three years prior to the purchase are eligible for a tax credit of up to $8,000. This credit is available for home buyers who purchased a home from Jan. 1, 2009, to April 30, 2010.

- Home buyers who have owned their primary residence for five consecutive years out of the last eight are eligible for a credit of up to $6,500. This credit is limited to homes purchased after Nov. 6 and on or before April 30, 2010.

Earned income tax credit

This tax credit is designed to help low-income, working families. Many households saw their income drop last year because of the economic downturn, so even if you weren't eligible in the past, you might qualify in 2009, says David Williams, IRS director of electronic tax administration and refundable credits. Another reason to give the EITC a second look: Eligibility requirements have been expanded.

car sales tax deduction

Taxpayers who purchased a new car, motorcycle, light truck or mobile home on or after Feb. 17, 2009, and before Jan. 1, 2010, can deduct sales taxes for the first $49,500 of the purchase price. You don't need to itemize to claim this deduction.

You can claim the sales-tax deduction even if you participated in the federal "cash-for-clunkers" program, says Amy McAnarney, executive director of H&R Block's Tax Institute. American Opportunity Credit

Congress is always looking for ways to help families offset the cost of college. This year, though, millions of families will be eligible for a new tax credit that's more generous and flexible than previous versions.

The American Opportunity Credit, part of last year's economic stimulus package, allows taxpayers to claim a credit of up to $2,500 for each eligible college student. The credit is calculated as 100 percent of expenses up to $2,000, and 25 percent of expenses above $2,000, up to the maximum.

Single filers with an AGI of up to $80,000 and married couples with AGI of up to $160,000 can claim the full amount. You can claim this credit even if you don't itemize, says McAnarney.

In addition, 40 percent of the credit is refundable, McAnarney says, which means you'll get a refund even if the credit exceeds the amount of tax you owe.

Contributions to Haiti relief

If you're a regular giver, you're probably accustomed to deducting the previous year's charitable contributions on your tax return. But taxpayers who donate to Haiti relief organizations don't have to wait until next year.

A special tax provision signed into law last month allows taxpayers who donated to Haiti relief organizations from Jan. 11 to March 1, 2010, to deduct the contributions on their 2009 tax return. You must itemize to deduct contributions to charity.