Now, about the possibility of more rebate money: For some folks, the news just gets better. "If you didn't get enough last year, you're going to get what's coming to you," says McFarland.

And finally, the best news of all: If in figuring your Recovery Rebate Credit amount you find that you actually were overpaid last year, don't worry about it. The IRS says you can keep the cash with no tax ramifications.

"If you got too much, congratulations," says McFarland.

Figuring your 2008 rebate credit
To find out whether you are eligible for more rebate money on your 2008 return, you'll need to fill out a work sheet, found in each of the 1040 instruction books.

And to do that, you'll need the statement the IRS sent you with details of the amount of last year's rebate. "I sent letters to all my clients telling them what to do, how to find that amount," says McFarland.

However, despite the efforts of tax preparers, some taxpayers still will have problems here. "A client just called. He couldn't remember the amount received. He didn't have the paper from the IRS," says McFarland. "There's going to be a lot of that, I think."

Robert D. Flach, a tax accountant in Jersey City, N.J., is anticipating his clientele will have similar issues. "I tell my clients in my annual January mailing to be sure to give me the notice they received from Sam regarding the amount of rebate received," says Flach. "Even so, I expect I will make good use of 'How Much Was My 2008 Stimulus Payment?' at the IRS Web site, as well as the service's online Recovery Rebate Calculator."

The IRS' online rebate tracking tool "How Much Was My 2008 Stimulus Payment?" will help you find out exactly how much you received in 2008.

Once you have that information, you can use tax form work sheets or tax software to determine whether you're due any additional rebate this filing season. Or you can plug last year's rebate figure into the IRS' online rebate calculator, which the agency says should be operational by early February. If you are not sure whether you qualify for additional rebate money on your 2008 return, the calculator will confirm your eligibility and how much Recovery Rebate Credit you may claim.

Who qualifies now?
If you got a $600 (or $1,200 if you're married and file jointly) stimulus check last year, you probably will not qualify for an additional payment this filing season.

But taxpayers who received no rebate money last year should run the numbers to see if they now can claim the credit on their 2008 return. So should filers who got less than the maximum amount last year.