HOUSTON --They say nothing's certain in life but death and taxes. But tax rules seem to change every year, and this year, thanks to some last-minute changes by Congress, you could be saving a bundle -- if you know what to look for. When Mike Arman and Ela Lugo started planning their new home, they decided to build it completely green. "We used a high-efficiency water heater," taxpayer Arman said. In addition to saving energy, they'll also be saving money on their taxes, according to H&R Block tax expert Elaine Smith. "The Home Energy Efficiency Credit is up to a $1,500 credit you can get by making improvements to your house that increase its efficiency," Smith said. This particular credit expired at the end of last year, Smith said, so you need to claim it on your 2010 return or lose it forever. Another expiring credit you'll want to claim for 2010? The "Making Work Pay" credit. "It's $400 for single people and $800 for people married filing jointly," Smith said. "It's a credit for people who worked, even if they worked a little." And speaking of paying, if you took the first time homebuyer credit in 2008, it's time to start paying it back, says IRS spokesperson Peggy Riley. "The 2008 First Time Homebuyer Credit acted more like an interest-free loan. So if you took the full credit of $7,500 for that year, you're gonna have to start repaying $500 a year," she said. But don't worry. Some other last-minute tax changes may work out in your favor. An inflation adjustment, for example, will increase the standard deduction and the income tax credit you'll receive. And that's not all. "Taxpayers stand to get thousands of extra dollars in credits and deductions this year, such as the tuition and fees deduction which will help a lot of parents and students who are in higher education," Riley said. So how do you make sure you're getting all the deductions you deserve? Riley suggests filing electronically, so you'll always be using the latest up-to-date forms. "The electronic programs will automatically ask you about credits and deductions that you may not even be aware of, and it will definitely help you get the best refund," Riley said. Some of these tax law changes were made so late that the IRS was not able to update their systems by the first of the year. They say some taxpayers may have to delay filing until mid to late February to get all the benefits they qualify for.