Apr. 18--A sharp-eyed pensioner from Providence noticed that the amount of federal income tax withheld from her pension-related annuity has declined. What's going on? Something that some pensioners -- and some workers -- will need to keep in mind:

Q: I receive an annuity and I notice that the withholding amount has been changed to less. Now, I don't understand why they are doing that, and [whether] this means at the end of the year when I pay my taxes for 2009, I will have under-withheld. So I'm just wondering what's going on.

-- M.C., Providence

A: It's the result of the federal economic stimulus legislation approved by Congress and signed into law by President Obama Feb. 17.

That law created a new federal income-tax credit, called the "Making Work Pay" credit. The credit will show up early next year, when you do your federal income-tax return for 2009.

But instead of making people wait until then to see the benefit of the new credit, Uncle Sam is distributing it now, in advance, through reduced withholding of federal income tax.

The Internal Revenue Service has changed the standard withholding tables that employers use to figure out how much federal tax to withhold.

Based on those tables, employers are now withholding a bit less than they did earlier this year. As a result, many workers are taking home a bit more in their paychecks, said Allan W. Graham, professor of accounting at the University of Rhode Island's College of Business Administration.

Having more money in your pocket now is good news. The idea behind the law was to put money into people's hands this year, to help stimulate the economy, said Cynthia Blanthorne, assistant professor of accounting at URI. But there can be a downside. For example:

--Pensioners: If you're receiving a pension, or a pension-related annuity, you may have chosen to have federal income tax withheld from your payments.

You probably have no earned income -- such as money from a job -- so you're not eligible for the tax credit mentioned above.

But the outfits that pay pensions and pension-related annuities are using the same tables that employers use, so they, too, are withholding less, said IRS spokesman Jim Dupree.

"The IRS has a single set of withholding tables because there are a myriad of possibilities, and separate charts for every circumstance would be unwieldy and impractical," he said.

Thus, as a general rule, "You're going to have a bigger tax bill next April 15 and probably not one you're prepared for. It could [come as] a surprise," Blanthorne said.