For most couples, a filing status of “married filing jointly” will produce the best outcome. If you know you need to file “married filing separately,” you can do it in many of those nine states (I recommend you research “community property” states first). But that would require you to create two single federal returns, two dummy federal returns and two state returns, for a total of six.

Tax returns for Registered Domestic Partnership, civil union, or same-sex marriage couples can be e-filed in all nine states that require them to file as married. In general, e-filing is the fastest way to get your refund. If you’re using software and you choose to e-file, you should prepare and file each of your single federal returns before you work on your “dummy” federal return and your state return. And remember to select only the state e-file button when filing your joint state return. This will send the dummy federal return with the state return only to your state, not the IRS.

In addition to the situation faced by same-sex couples, there are a few things all taxpayers should be aware of this year. Eighty percent of taxpayers are entitled to some portion of the economic stimulus money approved by Congress in 2009. This comes in the form of some new deductions and credits meant to help people through the struggling economy.

A couple of different homebuyer credits are available to people who bought a home in 2009. You could get up to $8,000 off your taxes if you qualify. You can also deduct a wide range of energy-saving home improvement costs.

If you bought a new car in 2009, don’t miss the opportunity to deduct the sales tax. If you were a college student in 2009, you might be able to deduct an expanded number of tuitions and fees. And donations to Haiti earthquake victims made this year can be deducted on your 2009 return.

If you’re not ready to file by April 15, you can file for an extension until October 15. But you will need to estimate any taxes you owe and send the IRS a check with your extension.