Unless you are schooled not just in tax law, but also tax law interpretation, revisions and calculus, you will need a professional tax preparer to guide you through the provisions that apply to capital gains from home sales, which make up only a fraction of the larger set of tax regulations. Here's a brief cheat sheet to give you some quick insights on what the law means to you if you sold a home this year. First, by now you should have long ago forgotten the old $125,000 tax exclusion on capital gains for home owners older than 55 and the "rollover" law that allowed you to defer paying capital gains taxes provided you purchased another, more expensive home in time. Those laws are history. The relief act's primary provision for home sellers is the capital gains tax exclusion -- when you sell your home, if you qualify, you can keep, tax free, capital gains of up to $500,000 if you are married filing jointly or $250,000 for single taxpayers, or married taxpayers who file separately. Your capital gain on the sale of your home is the selling price minus your cost basis. The cost basis is your purchase price, plus qualified purchase costs, improvements and selling costs, minus any accumulated depreciation, say for a home-based business. To qualify for the $500,000 or $250,000 exclusion, the home must have been your primary residence of record for at least two of the prior five years. If you have a second home that is also a primary residence of record, say where you live, go to work, send the kids to school, it will take four years to quality either or both homes. While you may qualify both simultaneously, the law only allows you one exclusion every two years. If, however, through some qualifying unforeseen event, such as a job change, illness or some other hardship, you are forced to sell before you meet the two-year residency requirement you can only prorate the $500,000 or $250,000 exclusion (not your specific gain) if you are forced to sell early. That means if you only live in your home one year -- half the required time to get the full exclusion -- and you are forced to sell for some qualifying unforeseen event, you can exclude from taxes, up to $250,000 in capital gains if you are married and file jointly or up to $125,000 for separate and single filers -- half the total exclusion allowed.

What are unforeseen circumstances? Multiple births resulting from the same pregnancy. The death of the homeowner, a spouse, co-owner or other person whose principal place of residence is the house that was sold. Divorce or legal separation. Health problems, if the primary reason for the sale is "to obtain, provide or facilitate the diagnosis, cure, mitigation or treatment of disease, illness or injury" of the home owner, co-owner, spouse or other resident. A loss of employment triggering eligibility for unemployment compensation. A change in employment status that results in the owner's inability to pay housing costs. The "involuntary conversion" of your home, say, when the state government or other eminent domain order requires you to sell your house. Military duty. Military personnel posted abroad for extended periods can stop the clock on the two-of-the-past-five-years provision until they return stateside.   There's another tax relief law break for home owners with home-based businesses. As long as your qualified home-based business is in the same dwelling as your primary residence -- rather than some unattached structure on your property -- you don't have to allocate a home sale's capital gains between the home and the business. Previously if you used, say, 10 percent of your home for a home-based business, 10 percent of the gain from a sale would be subject to capital gain taxes and you couldn't use the exclusion on that portion. For these and other tax law provisions, professional help is key to an accurate tax return