When I need tax advice, two things count: speed and accuracy. So I grabbed a stopwatch and put a reasonably tough tax question to several self-help sources. I searched books, software, online services, and the Internal Revenue Service's toll-free help line to see who would get me the correct answer most quickly. The result: The private resources all did pretty well. The big loser was the IRS help line, which came up far short.

I asked accountants Grant Thornton to cook up the question: What would happen if I bought a piece of real estate in 1990, sold it last April, but didn't begin receiving payments until June, after the effective date of the new tax law? In such an installment sale, would I have to pay the capital-gains rate that applied at the time of the transaction or the lower rate that was in force when I received the dough?

The correct response: The new 20% tax rate, rather than the old 28% levy. But if the property had been depreciated, the tax rate would be 25%.

In searching for the answer, I first needed to guess whether to look under "capital gains" or "installment sales." With computer software, the search functions tended to show the answer under capital gains. Tax books, meanwhile, seemed to prefer installment sales--which is closer to my own logic. Eventually, though, all the sources gave me the correct answer. But when I put my stopwatch on them, the field broke out into three distinct groups.

THE WINNERS. The winners, at three minutes apiece, were the tax book J.K. Lasser's Your Income Tax and the software program TurboTax Deluxe. A minute behind them was Internal Revenue Service publication 537 (installment sales)--which I got by clicking TurboTax's government-instructions icon. IRS forms and publications are included as part of both big tax-software programs--TurboTax Deluxe and Kiplinger TaxCut Deluxe.

In fourth place was the IRS Web site (www.irs.ustreas.gov). It took a poky nine minutes to get the right publication, mostly because downloading and printing were pretty slow on my home computer. Of course, the IRS Web site looks better when you figure the time it takes to go to the store and buy the other resources.

Kiplinger TaxCut Deluxe software was a distant fifth, at 16 minutes. It found the rules for depreciated property quickly, but I struggled to ferret out the installment-sales answer.

Bringing up the rear was the IRS phone line. After sending me through three layers of automated routing, I finally got a recording that told me to press 4 to listen to a tape. I did, and instead got a message that asked me to leave my name and phone number and promised a call back within three days. A Ms. Brown phoned back with the correct answer in less time than that. But I still waited 51 hours.

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