Every year, the tax rules change a little. That provides job security for tax preparers such as H&R Block (NYSE:HRB) and TurboTax maker Intuit (NASDAQ:INTU), but for taxpayers like us, it can be more of a mixed bag. Since paying attention to these seemingly small tweaks can net you thousands, here are a few new rules (and little-known numbers) to watch for.

  • The Child Tax Credit is set to decrease from $1,000 per child in tax year 2009 and 2010, to $500 per child in 2011. If you and your child(ren) qualify, it offers a hefty tax cut -- especially this year. Remember that a credit is better than a deduction, since it reduces your tax bill dollar for dollar. If you're in the 25% tax bracket, a single eligible credit is like having $4,000 of taxable income erased. If you have three children ... well, you get the idea.
  • There's a "Making Work Pay" credit that can put as much as $400 in your pocket (or as much as $800 for married folks filing jointly). It represents 6.2% of earned income, for those who qualify based on adjusted gross income. You may already have seen its impact via a reduction at work in your withheld taxes.
  • The Hope Scholarship Credit, which formerly offered as much as $1,800 for most students for the first two years of college, has been replaced by the American Opportunity Credit, offering up to $2,500 per student annually for those who qualify.
  • The maximum IRA contribution for those who qualify is actually staying the same for 2010 -- it's $5,000 for most of us, and $6,000 for those 50 or older. IRAs are good places to stash dividend-paying stocks such as Lockheed Martin (NYSE:LMT), DuPont (NYSE:DD), or Chevron (NYSE:CVX). If you play by the rules, Roth IRAs will let you withdraw everything tax-free -- making them especially attractive places to park stocks you expect to soar. (Of course, if they crash, you won't be able to deduct the loss. Invest with caution, Fools.)
  • Because of low inflation, some feared that contribution limits for 401(k) accounts would be lowered for 2010, since they're supposed to be adjusted in line with inflation. But they remain the same in 2010, at $22,000 for those 50 and older, and $16,500 for the rest of us. Apparently, Uncle Sam is taking pity on the many of us who have not saved enough, and helping older Americans try to catch up.
  • The Wall Street meltdown that knocked huge companies like Citigroup (NYSE:C) and AIG (NYSE:AIG) for a loop also battered gobs of homebuyers, some of whom had a portion of their mortgage debt forgiven. Under standard IRS rules, the value of that aid would count as taxable income, but the Mortgage Forgiveness Debt Relief Act waives that, for those who qualify. That's a very big deal; if you had $40,000 of debt forgiven, a 25% tax on that would amount to $10,000!
  • Similarly, unemployment income is usually taxable -- but for 2009, you can exclude the first $2,400 you get.

There are lots of other new developments and tweaks to taxes for 2009 and beyond, including tax breaks for buying a car and making energy-related improvements to your home. It can pay off big time to learn more about them. Good thing we've got a Tax Center for just such a purpose!

Longtime Fool contributor Selena Maranjian does not own shares of any companies mentioned in this article. Try any of our investing newsletter services free for 30 days. The Motley Fool is Fools writing for Fools.