Some types of insulation can qualify for energy-saving tax credits under a federal program set to expire Dec. 31.

Gasoline and other fuel prices are soaring, but Congress and the Bush administration can’t reach a simple agreement to extend a tax-credit program that has saved billions of dollars by making energy-saving improvements.

Q: About a year ago, you wrote about some of the new federal tax credits that homeowners could get if they made energy-saving improvements to their house, but you also said that the credits would expire at the end of 2007 unless Congress and President Bush agreed to extend them. Did they extend them?

A: No, at least not yet. The tax-credit program has saved collectively billions of dollars for property owners who’ve made energy-saving improvements to their homes in the past several months, as well as those who purchased electric, hybrid or other alternative-fuel cars. It also has helped to reduce our reliance on foreign oil, postponed the need to build some new power plants and refineries, and has even been credited with slowing global warning.

Despite such obvious benefits, Congress and the Bush administration have been unable to reach a compromise that would extend the energy-saving tax credits beyond its Dec. 31 deadline.

A last-minute deal to keep the credits in place for at least another year was still trying to be negotiated in mid-November, but smart homeowners who’ve been thinking about making energy-saving improvements should probably do the work now – before the end-of-the-year deadline approaches – instead of hoping that the same tax credits will be available in 2008.

Homeowners who install energy-efficient windows or doors now can be eligible for up to a $500 federal tax credit. It’s important to note that tax credits are a lot more valuable than tax deductions, because every $1 you have in credits knocks an equal $1 off your federal taxes. That’s a lot better than a tax deduction, such as the one you take for your mortgage-interest payments, because a deduction saves you only 15 cents or maybe 35 cents for every dollar you can deduct based on your earnings.

You may also qualify for a $300 federal tax credit if you install a special type of energy-saving water heater or air-conditioning system by the end of this year, and up to a whopping $2,000 in credits if you put in solar-powered panels.

Many state governments and local utilities also provide tax incentives or even rebates for energy improvements, but you may lose the opportunity to bolster your savings if you don’t do the work by the time that the federal credits are set to expire Dec. 31.

Q.: My mortgage payment is due on the first day of each month, but I don’t get hit with a “late charge” as long as the bank gets the check by the 15th of each month. Sometimes, I don’t have enough money in my checking account to pay the money at the start of the month, but I always pay it by the 15th, so that I don’t have to pay a late fee. Is this OK, or is it messing up my credit record because the bank sometimes doesn’t get its money on the first?

A.: Most banks require their borrowers to make their mortgage payments on either the first or 15th day of the month. But many of those lenders allow a 15-day “grace period” in which a late fee will not be assessed (nor will the loan be reported to a credit bureau as “delinquent”) if you pay the bill within two weeks after its due date.

Although your letter states that you’ve sometimes paid the mortgage bill a week or two after it was technically due, the fact that you have never been assessed a late-charge suggests that you are among those borrowers who have a grace period and therefore don’t have to worry that your slightly laggard payments will negatively affect your credit score.