Thinking of sprucing up the old homestead to make it a little more energy-efficient and maybe save yourself some money on utility bills?

Um, you may want to wait a few months. The good news is, Congress wants to give you a helping hand in paying for some of those upgrades; the bad news is, the help isn't coming right away, and it isn't all that much.

The huge energy bill that lawmakers managed to disgorge last month before going home for their August break includes about $14.5 billion in energy "incentives," and while the bulk of this goes to businesses, it includes some benefits for homeowners and car buyers as well. The new benefits are mostly tax credits, rather than deductions, meaning they reduce your tax bill dollar for dollar, and thus have the same value for all taxpayers.

However, the bill, which President Bush is expected to sign tomorrow, specifies that many of the tax breaks it provides are available only for items purchased or placed in service after Jan. 1, 2006.

Maybe that isn't such a bad idea, though. At least it will give suppliers and builders time to figure out exactly what qualifies, and possibly what the best combination of benefits might be.

For homeowners there are two key provisions to look into.

The first allows a 10 percent tax credit for improvements to the energy efficiency of existing homes, up to a lifetime maximum per taxpayer of $500. The credit applies to property placed in service in 2006 and 2007 only.

The second offers a 30 percent credit for the purchase of certain kinds of solar-powered water-heating systems, photovoltaic equipment (which converts sunlight to electricity) and fuel-cell systems. The maximum credit is $2,000 for solar systems and $500 per kilowatt of fuel cell capacity. This one likewise applies only for items placed in service in 2006 and 2007.

There are also some business provisions -- for energy-efficient houses and appliances -- that may help homeowners, though that will be contingent on the businesses passing along some of the savings to consumers.

Finally, there is a new batch of credits for energy-efficient vehicles. Some are new, some replace deductions allowed by current law, and they have lots of different expiration dates.

Homeowners will likely find the 10 percent credit the most appealing. It applies to improvements to a building's "envelope," so such things as insulation improvements, metal roofs coated with heat-reducing pigments, and energy-efficient windows, doors and skylights are eligible. The maximum credit is $500, meaning a homeowner would have to do $5,000 worth of work to get the full amount, but only $200 of the credit can come from expenses for windows.

This same 10 percent credit also applies to a list of specific items, each with its own maximum. Some of these are a bit on the esoteric side, and you may need to consult both your plumber and your accountant to figure out whether they are useful.

On the list are advanced main air-circulating fans, which qualify for a credit of up to $50, and certain natural gas, propane or oil furnace or hot water boilers, which are eligible for a credit of as much as $150. Also, some electric and geothermal heat pumps qualify for a credit up to $300.

"You take those amounts, add up those from [any improvements you've made to the envelope], then apply the $500 maximum, with not more than $200 for windows. So it is a quite modest amount, considering prices nowadays," said Bob D. Scharin, editor of Warren, Gorham & Lamont/RIA's Practical Tax Strategies, a monthly publication for tax professionals.

The credits can be taken on 2006 and 2007 returns, but the $500 total is a "lifetime" one, meaning that you can't increase it by spreading the work over two years. The credit also applies only to your "principal residence." The law doesn't define that, but presumably it means you can't get it for improvements to your beach house unless you really live there.

Homeowners interested in making use of advanced technology in their houses can consider the 30 percent credit for solar water-heating, photovoltaic and fuel-cell equipment. It apparently can be taken in addition to the 10 percent/$500 credit.

While this credit is more generous, it has some quirky limitations.

First, these gadgets can't be used to heat swimming pools, hot tubs or the like.

"If you can afford those luxuries," Scharin observed, it might make sense to assume you don't need help paying for the equipment. "On other hand, if the thrust of the bill is to improve energy efficiency, use should not be as relevant."

Second, the bill specifies that fuel-cell equipment must be installed on the taxpayer's principal residence to qualify, but photovoltaic and solar water-heating equipment need only be installed on the taxpayer's residence. "It thus appears that photovoltaic [equipment] and solar water heating installed in a second home will qualify for the credit," according to an RIA analysis.

On the automotive front, the bill provides credits not only for the purchase of hybrid internal-combustion/electric vehicles, but also cars and trucks that employ advanced "lean burn" fuel systems, or run on alternative fuels.

The credit varies depending on the vehicle's weight, fuel economy and the amount of fuel it is expected to save over its lifetime. This calculation is so complicated, Scharin said, that consumers will have to rely on car manufacturers to figure it out and, presumably, include that information with the car's specifications.

Another "odd thing" in the bill, Scharin said, is that it limits the full credit for hybrid and lean-burn cars and trucks to 60,000 vehicles per manufacturer, after which it is reduced under a complex formula related to when the vehicle was produced.

This is not a joke, at least not an intentional one. It is ostensibly meant to encourage companies that haven't been doing much with this technology to get going, but it may also be a shot at Honda, Toyota and others that now mass-produce qualifying vehicles. It would also seem to be a provision that oil companies like.

"Aside from all the other questions you have to ask at the dealer," Scharin said, "you now have to ask, 'Is this vehicle really eligible' " for the full credit?

How this is to be enforced is another mystery.

The Treasury Department last week ruled that if an employer provides a worker with a cash allowance for tools, and doesn't base it on the worker's actual expenses for tools and doesn't require receipts, then the allowance is taxable income to the workers.

Typically, reimbursements for tools under an "accountable plan" are excluded from taxable income, but the ruling "clarifies that employers using accountable plans . . . must substantiate the expenses reimbursed and, to the extent the plan provides payments before expenses are incurred, the plan requires the employee to return amounts in excess of the substantiated expenses," the department said.

Fidelity Investments said last week that account balances in the 401(k) plans it manages averaged $61,000 at the end of last year, up 10 percent from 2003 and the highest since 1999. Worker participation in the 10,800 plans was unchanged at 66 percent of those eligible.